XSS worm on my InfinityFree site?

OK so you’ve been a bit unclear. I thought you are going the other way around but actually no. In this case that script has no influence here, it’s not the culprit. Now if you try to embed a random YouTube video it may not work at all. This is because YouTube can reject embeding on their end. If it is your video, you need to check if you have allowed embeding on the video you wish to use. If it is someone else’s then there’s a high chance that it doesn’t allowed to be embeded in the first place.