I think you can now do this with BBM 5.0.0.33 but obviously that only works if the recipient has a BB too.
(Oh, and they would need to have a version of BBM5 I think.)
Posted from my CrackBerry at wapforums.crackberry.com
I think...if you don't see an option to send a video as a MMS, then your video file is too big. You can change the video format to mms mode before you record a video and you can send a longer video but the quality is bad.