How can I do that? I would like them to be able to click play, pause, volume, and of course...fullscreen.
I heard you can do this with QuickTime or something? Anyone have any suggestions?
EDIT: These video files are on other people's servers. (We're a search engine)
I just want to pass take the URL of the .mp4 file...and do some java-script to let the user play it.
Yep, Flash is fully capable of streaming most if not all major video formats at this day in time. You don't even have QuickTime, Windows Media Player, Real Player or any other streaming media player installed for it to work. All you need is to look at the available source code examples to get a better idea of how to achieve this fluent design for streaming multiple formats, or what's better known as Flash Video Format [FLV].
Here's one place to get more information on the Flash Video Format: Wiki: Flash Video Format, and here's a place to view source code on how others incorporate FLV into their Flash interface: Flash Based FLV Player
Cortado is a Java applet capable of playback of MJPEG, Ogg Theora and Vorbis.
The next-generation HTML5 specification has a <video> tag, though browser support at the moment is somewhat less than ideal.
Along those lines, Video for Everybody will attempt to use <video>, and fall back to a QuickTime plugin if it is unavailable, and fall back to a Flash plugin if that is unavailable.