Unfortunately, there is no single search that will display all streaming video in the online catalog.
However, if you search the Library Catalog by title, subject, etc., all matching streaming videos will show up. You can use the categories in the left column to tweak your results:
We also have several special collections of streaming video, including databases:
Arts & Humanities
Health & Medicine
Science & Technology
If you need a film or other type of media for your research, you can acquire it through Interlibrary Loan just as you would a book or article. You can also check with your local public library.
A film you need might also be available via a streaming service such as Netflix. Hulu Plus contains many films in the Criterion Collection, and occasionally some are made available to stream freely. However, these services require a paid subscription (though many offer a free trial).