This is part of the dynamic HTML model although the dynamism is inside the asset encapsulated by the object.
You can playback a video clip or traverse a VRML panorama at any location where an image would have been placed.
If you use the DYNSRC="..." HTML tag attribute, you should not specify the SRC="..." HTML tag attribute.
The loop property of the IMG object controls how many iterations of the animation take place.
This is not even remotely portable so it is not recommended that you use this unless your user base is captive and using a controlled release of the MSIE browser. Using a plugin video player is far more portable.