extremeshannon - to answer your question directly (which is why I originally asked if you were talking about mp3s specifically!) ID3 tags are for MP3 files only (and much more rarely AIFF and MP4, but are not really well supported). Bottomline is, you can use any ID3 tagging program you like, but they will only tag MP3 files as that is what ID3s are for. Attempting to add ID3s to video files will probably break the container (although it is likely to be ignored as a corruption) and in any case LMCE will ignore them, as it should.
There are many, many different video container formats, and all the newer types have tagging systems, but none are container-independent/standard and are not supported by LMCE. Realistically, most video media files come from 2 main sources - ripping DVDs or downloads. Ripping a DVD on LMCE should grab the metadata anyway. Downloaded video amost never has tagging even when the container supports it, in which case you need to tag it manually any way, so you might as well do it through the LMCE web admin