To insert YouTube videos in comments (or in posts), please do not copy the ‘embed’ code from YouTube, because it is currently incorrect and will not work.
It’s really very easy to do. Here is what works -
Please notice that the url must be a proper one, not a shortcut version which contains tu.be – ie. a full stop in between the “tu” and “be” of “tube. You can get the correct url from the address bar when you view the video on the Youtube site.
Notice that there are no spaces and that there is an equals sign between ‘youtube’ and the start of the url.
Further observe that there is only one ‘get’ parameter (stuff after the question mark). If there is an ampersand (‘&’) in the url (or more than one), remove it and all the text that comes after it. The url must finish after the “v=string representing the actual video“. In this case v=dFdas-kMF74
Don’t forget to start with a square bracket, and finish with one.
Other ways of doing it may work, but this is the only way that will always work under any circumstances.