Does anyone have any recommendations have a good cross platform digital asset manager that manages a collection of photos (and if possible) videos that allows you to add metadata to files to easily find relevant pictures.
Great suggestions above. you can check out Phraseanet as well (open source DAM). http://www.phraseanet.com/en/
I already mentioned two in your other QA:
Then there is also Extensis Portfolio Server
I also suggest looking the following links