I think there are several things to think about when making a convention video.

Are you making the video for yourself, or for your potential viewers? If the former, then just make the kind of video you want to watch. Do you just like pure technical juggling? Then fine, stuff your vid full of nothing but the hard tricks. But if you think about the convention reviews that people post online, so often their convention experience is not just about the juggling - it's about the whole atmosphere and vibe of being at the convention: the people, the workshops, the games, the messing about with plastic ducks (or whatever...). Try to capture some of these kind of moments in your filming, and your video will be more likely to give a good feeling of what the convention was like as a whole, and not just show "what tricks people were doing there".

Spend some time thinking about what your soundtrack will be. If you are far-thinking enough to decide this *before* the convention, you can even set up some shots that will edit particularly well to the music. Also, try to edit to the music, rather than doing all your editing first, and then throwing some music on top of the footage. This will mean much more work, but will result in a more satisfying video.

Get a tripod. Shaky handheld footage should always be a last result.

Learn to use your camera correctly. Read the manual. Learn about manual focus, white balance, and exposure. Don't zoom in mid-shot - it will look rubbish.

Don't make people look bad. Bin that unflattering footage. Unless it's funny.
Check your titles for spelling mistakes. Twice. And make sure you've spelled people's names correctly. And check your titles for spelling mistakes too. ;-)

After you've finished editing, don't ruin it all by using poor compression. See this article in the IJDb compendium for hints on that.

And lastly, don't spend your entire convention "behind the lens" - remember to have some fun yourself too!

The Void