as far as I know MVI is outdated. It's been used for packaging audio & video to DVDs along with interaction (like menu selection). I don't think any web player supports this.
the site supports pretty much
all regular formats (avi .mkv .mov .mp4 .mpeg .mpg .m4v .vob .wmv and more). if you have trouble uploading videos let me know.
FYI: I'm currently investigating an ongoing issue regarding uploading videos. if you have issues, it might be also related to that. you can track the progress in
this thread.