Are most flash video players created all programmatically? Or they done using static buttons that are referenced in classes? Is it better to create all your buttons on the fly or does it not really matter?
Most video players aren't using AS3 yet, but different ones do it differently. It depends on what level of configurability you want. Personally I mostly do it programmatically so that I can configure everything with an XML config file or FlashVars.
I've found the easiest way was to use AS3 video components and customize them as needed. For example, the play head does all the scrubbing for you automatically, but you can control placement and design.
Here's a great tutorial: http://www.adobe.com/devnet/flash/articles/skinning_as3_flvcomp_03.html
I don't think there is much difference internally if you use static buttons or programmed ones. Its more a personal preference. If my buttons have been complexly designed then I would import them, then reference them in classes; but if they are simple boxes and text, for example, then I would program them as it gives better control. I personally prefer all things being in classes not on the stage, but sometimes its easier not to.
here is a good video tutorial http://www.thetechlabs.com/tutorials/audionvideo/how-to-build-a-as3-videoplayer/
check out the swfobject documentation for good flashvar implementation http://code.google.com/p/swfobject/wiki/documentation