ya kinda alot different but similar at the same time.
find the embed code for the video you want, go into add video, and there should be a little link that says something like "click here if you really want to ignore me and embed anyways", click on it and paste the embed code and voila.
for embedding into threads, there are two ways to do it. easiest being, go into your settings and turn of the fancy editor. once you've done that you can simply paste the embed code into the thread and boom!! if you like the fancy editor, click on the little f icon on the top of your little text box when you hit reply to thread, and then paste the embed code into there.
here is a link to a good practice thread and goes into detail about it.
https://newschoolers.com/web/forums/readthread/thread_id/524110/
hope that helps.
