He isn't watching the latest Coldplay video or catching up on an episode of "Alias" as a way to relax before the game.
Jennings is doing some last-minute cramming: The Rockies' video staff has downloaded every Marlins hitter into his iPod, and Jennings is figuring out how to pitch to them. He watches frames of himself delivering the pitch, followed by the result of the play. Everything else is weeded out.
"It's a good way to refresh yourself on how you got guys out," Jennings said. "It's an amazing concept."
The Rockies have taken the iPod beyond entertainment. And the idea has caught on — teams such as Florida and Seattle have called the Rockies to explore their innovative use of the iPod.
"It wasn't like we invented the wheel," said Rockies assistant video coordinator Brian Jones, who came up with the idea after the video iPod was released last November. "We're using Apple's technology as best we can. We figured if you can watch music videos by rock 'n' roll and by country, why can't you watch at-bats by San Francisco and pitches by Jason Schmidt?"
Over the past two decades, video has become common throughout the league, as it is with football. Teams have tons of film to help players study their opponents and their own quirks. In the last few years, players have been able to take home DVDs to watch on their laptops.
Now, all that information is in the palm of their hands.
"They can do it on their time, they don't have to be here or they don't have to be behind a desk watching a laptop. They can be at home, on the airplane or even in their locker," Rockies video coach Mike Hamilton said.
Red Sox reliever Mike Timlin said he isn't sure the trend is a good one.
"Improved the game for us pitchers? No," he said with a laugh. "There's only so much you can do to get the guys out. These guys have a better idea and a better understanding. You have to rely on your catchers. You had to before video."
New York Mets manager Willie Randolph doesn't have a problem with a player analyzing video, but it wouldn't have been for him. Randolph, a former All-Star, preferred extra batting practice to extra film sessions.
"I think it's overrated personally, but that's just me," Randolph said. "I'm from a different school."
The Rockies have downloaded video clips into the iPods of 14 players so far. For the hitters, they'll store every at-bat and download performances of upcoming pitchers. A 60-gigabyte iPod can hold roughly five seasons' worth of a player's at-bats. Pitchers can get all their performances, along with opponents' at-bats.
Jones has permission to take iPods from players' lockers to update them, and when the Rockies are on the road he compiles DVDs of their play and loads video onto the iPods when they return home.
"I take care of it all," Jones said. "It just takes a few minutes. It's like putting a song on from iTunes."
After seeing what the Rockies were doing, the Marlins left town with their own iPod ideas.
"I've never heard of that," Florida pitcher Dontrelle Willis said of storing starts on the iPod. "Oh man, that would be convenient."
Rockies second baseman Jamey Carroll overheard Hamilton talking about the concept at spring training and showed up the next day with his video iPod, ready for it to be stocked with footage.
"I don't put movies on it," Carroll said. "I want to save all the space for hitting."
The club doesn't buy the iPods for the players. It's a $399 investment for the 60-gigabyte model (the 30-gigabyte version costs $299). The Rockies have, however, purchased five iPods for general manager Dan O'Dowd and several scouts.
Colorado's minor league hitting coordinator, Jimmy Johnson, has an iPod filled with video of players in the farm system. If a player is struggling, Johnson can compare his swing from the past with his current swing, and fix it accordingly.
The iPods came in handy before June's baseball draft, too.
"That way the scouts could compare a prospective draft pick in North Carolina with one in California," Hamilton said. "You'd have a real good comparison. The game is so visual now. This helps."
The small screen size — 2.5 inches — hasn't been a problem, either.
"Six or seven guys can't sit around and watch it," Hamilton said. "But if you watch it yourself, it's not that much different from watching a large screen."
Boston slugger Trot Nixon said he watches standard video when he needs to, but doesn't obsess over analyzing his swing.
"If something doesn't feel right I'll look at the video or ask some of the teammates that have played with me for a long time," he said. "I've seen guys go back to the video after every at-bat. I was guilty of doing it at times, but I was only upsetting myself more and more: `Look at that pitch the umpire called. Why did I do this, do that?' I've got to go out and play right field. I've got to leave it there."
Jones thinks his iPod idea soon will be used across college and professional sports.
"We're always trying to figure out the easiest way to help our players," he said. "In the old days, when you had a VCR, you had to go through so much tape. Now it's so much easier and portable. You don't have to search for two hours to find that one swing on that one day."
Rockies slugger Todd Helton has every hit since 1998 stored by month on his iPod, which he uses to help him find his stroke whenever things start to go bad at the plate.
"When the swing doesn't feel right, I look at it to capture how I was feeling or which one of my 300 stances I was in at that point," Helton said. "Baseball is such a messed up sport and it's so hard, sometimes you need to go back and look at the good things."
Helton frequently checks out his August 2000 file, when he had 50 hits and batted .476 for the month.
"If you look at my swing then, it didn't look like I was swinging too hard, and it didn't look like I was trying to do too much," Helton said. "I was putting the head of the bat on the ball, and that's what you're trying to do."
Helton was leery about showing too much enthusiasm for the Rockies' cool new toys.
"We're trying to get all the advantages we can," he said. "We don't want anybody else to get this."
Willis left Coors Field excited about all the possibilities of this new application of technology.
"Anything you can do to help yourself get ready for (games) is a good idea," he said.