Check Photobucket and see if there is a restriction on the video size. If shooting in high quality a short video, around a minutes or so, can be pretty large in file size.
If size is the issue, then you may want to reduce the file size in the future before filming or use a compressor to shorten the file size. There are a few in the Market worth taking a look at.
For alternatives, you can't go wrong with sharing a video on Youtube