Aside from when the mods broke a few years back, the embed has always been there for at least YouTube and Vimeo. The Social Media embeds for Facebook and twitter are more recent, I've forgotten when but at a rough guess about 7-10 years. Its not set to autoplay and the size is constrained, so as far as screen space is concerned it probably takes up less space than the average image. People tend not to notice it because its not abused or overused.
I must admit I personally preferred the old Ohara YouTube mod which relied on the user to insert the BBC tags, I did actually have a slight moment of sadness to ditch it as I've used it practically since the author brought the mod out and have several convo's with him over the years when it comes to bug fixes, but unfortunately changes in the core code caused conflicts if you tried to use more than one media type.... and none of the other mod authors offered to try and get it to work in tandem with multiple media types
OTOH lots of users didn't know what format to use or how to insert and there were plenty of times when the code had to be fixed by our admin team. I fully comprehend why the author of the current modification has set it to auto detect the media type and apply the relevant code - 1) Dramatically cuts down the chance of user error. 2) Because it can deal with about 30 different plug-ins (I dont have all options turned on), it would require a long line of BBC buttons above the post reply box.
As mentioned earlier, I did test several different plug-in mods, but this was the most elegant and best suited to our forum.