Bit of an update regarding posting videos.
If the video is on YouTube, it is no longer required to use the VIDEO tags. That being said, you still probably should use the tags just in case of any forum updates that we may get in the future. Also, it should make no difference whether the YouTube video uses HTTP or HTTPS or if you're using the long or short URL links as all of them should now embed.
The VIDEO tags will still be needed if the video is hosted on other sites like DailyMotion (when you click the VIDEO tag button, the pop-up window you get should state which video services will work). If you're trying to post a video from a site that is not included amongst the ones listed in the pop-up wndow, then it may not embed at all and you'll likely have to just post it as a URL link (so as an example, for anyone like me who sometimes watch videos on Youku, those can only be posted as URL links since they can't/won't embed here).