Unless I'm missing something here with oEmbed, you don't need any complicated libraries.
Assuming for example the two most common video services you use on a particular site are YouTube and Vimeo, you would simply need to check the URL that has been input into a text field (or URL field or whatever) in PW for either "youtube" or "vimeo" and then use CURL to do either:
https://www.youtube.com/oembed?url=http%3A//www.youtube.com/watch?v%3D-UUx10KOWIE&format=xml
or:
http://vimeo.com/api/oembed.xml?url=http%3A//vimeo.com/7100569
and parse the XML into something useable in a template.
I think that the second and third solutions linked to in previous posts poll those two websites (noembed and autoembed), adding another unnecessary link which relies on those websites being online all the time (I might be wrong).
I would imagine that a module for oEmbed would "simply" (haha ) detect which site, if any, the URL relates to, fetch the XML response for that site's video service and turn it into something useable - so a normal module call for this in a template would probably be about 4 lines or so and could also allow you to specify dimensions for the video and then do all of the outputting for you.
You could then theoretically just dump YouTube/Vimeo/whatever URL's into the middle of your TinyMCE content if you like and have the module parse the $page->body field, turning these links into embedded videos if you really wanted to.
I'm tempted to build this module myself as I've currently only managed to build support for YouTube in my current project (using a lot of Google YouTube API files that now appear to be unnecessary), but it'll be a few weeks before I got around to it so if anyone else wants to have a go at it feel free.