Too many variables. Overload! random suggestions to follow.
For movies you download, OPlayer HD may work.
Movies on other sites, depends on whether they detect your mobile browser, allow it, and server media using HTML 5 instead of Flash.
There are also several other apps; some free, some pay, some a combination.
Crunchyroll, ABC, Hulu Plus, PBS, TED+SUB are some of the ones I have.