Is there a way to play video on a webpage with javascript without Flash Player ?
HTML5 will support video playback via the <video/>
element. See here for more details, and here for implementation details.
There's always the poor man's alternative of just loading a bajillion individual frames as .gif/jpg/png and having javascript display them in sequence. It would be absolutely horrible for bandwidth and memory usage, and of course no audio, but it would (somewhat) simulate video being played.
Of course, on Windows platforms, you could use ActiveX and/or embed media player and play avi/wmv files as well, without ever touching flash.
You can always embed Windows Media, Real Player or QuickTime directly into your page. There's also Silverlight, if you're simply looking to avoid Flash. If you don't care how it looks, you can build a low quality player in Java. On some browsers, there's the HTML 5 video tag, but there's no real standardization on CODEC just yet.