In case you missed the news over at the Google Code Blog, you can now upload videos to Picasa Web Albums using its Data API. It's as easy as uploading a photo -- a POST to the album URL with a video format (video/quicktime, for example) specified as the Content-Type. You can also choose a custom thumbnail for the video. The Java client library is currently the only library with support, but the snippet to upload a video and set the thumbnail looks like this:
MediaFileSource myMedia = new MediaFileSource(Read up more in the docs.
new File("/home/liz/birthday.mov"), "video/quicktime");
PhotoEntry returnedVideo = myService.insert(feedUrl, PhotoEntry.class, myMedia);
MediaFileSource myThumb = new MediaFileSource(
new File("/home/liz/birthday_title.jpg"), "image/jpeg");
PhotoEntry updatedEntry = returnedVideo.updateMedia(false);