For a selection of short videos for the Mathematics Classroom try the Class Clips from BBC Learning Zone. Choose Primary (5-11) or Secondary (11-18) a subject and a topic. Note that each video has several keywords making searching possible.
A job for the summer holidays – make it easier to find resources on this site!
With this mission in mind I have added a Search page to highlight the Search function.
On the subject of searching, I recommend both Evernote and Diigo – I use both. This morning I was thinking about a resource I need for September (I think I need a holiday!) – for a making polyhedra session and remembered I had bookmarked it on Diigo; so from approximately 2000 bookmarks I had what I wanted in seconds!