The iframe is what triggers the content block to lock up, though. Otherwise, without the iframe inside the content block, yes, the content block functions normally. Let me reiterate the problem:
1. I put the content block on the page.
2. I go to the HTML view on the content block. I paste the YouTube iframe's html into the text editor.
3. I switch to Design view. The YouTube video player loads in the text editor. It looks fine. It works fine. No problems there. If I stay in Design view, I can add text around the video however I see fit. Everything works fine.
4. When I switch back to HTML view, and I try to insert my cursor into the text editor, I can't. I can't select any of the HTML text, either. I can hit save. I can go back to Design view. Basically, I can use any of the buttons, but I can't get my cursor inside the text editor.
Does this make more sense? If not, I can try to make a video that illustrates the problem.