How to show a video on a web page using Python?

To show an image on a web page I need to use <img> tag in the HTML code and in this tag to "point" to an image file location on my web-server. Can display video in a similar way? I just use a tag (for example <video>) and within this tag I point to avi or mp4 file located on my web-server.

I suppose that it cannot be done in the above described simple way. So, if it is the case, how can it be done?

I need to notice that I do not want to use videos provided by youtube or other web-services. I want to have a site where user can submit videos (for example as mp4 or avi files) and the site should be able to show these videos to other users.

Does it mean that I need to be able to convert avi and mp4 files into a flash-format? Can Python do it? Should I use HTML5 functionality instead of flash?