Some thoughts:
1) Don't scroll the name. It's a bit hard to read for some people (mainly me) with all the stuff going on the screen, it's just one more graphic to track.
2) Make the name bigger. It's their frag!
3) Post the division along with the video. Maybe everyone knows all our games by heart, but I don't. I'm thinking like those video clips of college basketball games on the news where the transition includes the logo of the team?
4) When fast forwarding, put some kind of interactive graphic on the screen. Blinking fast forward arrows ( >> ), tape static like a VHS tape... I got disoriented every time it happened because the transition from "normal" to "fast forward" was jarring.
5) When showing off strings of kills, put up a hud counter to go along with it. Maybe a bell ding for every one. Just to make it that much cooler.
6) I know it's Top 5 Frags, but maybe add something else. A "Top Fail" or a "Blooper." I mainly add this so I can put in an entry. This slot would be for that video submitted of the very obvious spy in TF2 failing to kill anyone, or a spy decloaking in front of a sentry gun, or a CT throwing a flashbang into his own face. Everyone can be a pro fragger, but failing with style?
7) During transitions, advertise the server it was taken on. =(eGO)= 24/7 Turbine! as part of the transition would tie in the advertising aspect a bit tighter.
8) I actually didn't mind the music, just don't pick some crappy CD single and slap it on the sound track. Something active, but out of the way, so the video takes center stage.
9) In each post, you should advertise how to submit videos for the next frag video. So that somebody who just finished watching these frags, with a video on their HD, can turn right around and toss their hat into the ring.
I'm, personally, not against the "string 'o frags" format. In some games, especially TF2, where anyone can get a lucky crit, the impressiveness is the guy blowing up 22 people in a row, or sapping the entire intel room themselves, or breaking up an uber charge with nothing but a sniper rifle.
