Videomaker – Learn video production and editing, camera reviews › Forums › General › Video and Film Discussion › Where to get free stuff? › digital juice and footage
digital juice and footage firm are a good place to start.
If you have After Effects or Motion there are some decent backgrounds included…or you can just make your own with these programs…
AE has a brainstorm feature where you can make a simple background and it willcreate unlimited backgroundsbased on specific features you select from that background.
http://library.creativecow.net/articles/rabinowitz_aharon/Brain_Storm.php (AE brainstorm reference)