This sounds interesting. Masher promises to
mix your videos, photos and library clips from BBC motion gallery, mash them by adding words, music and effects and then share by email or social network all for FREE..sounds too good to be true.

Just did a really quick mash. This seems really cool. I'm not sure you can download your final mash; looks like you can only send a link. But I've discovered if you have DownloadHelper as an extension of Firefox, you can download the video clips and music from BBC motion gallery. That in itself is a great resource. But I've just discovered that you can go directly to BBC Motion Gallery for royalty free footage and music..so maybe that's even better !