Can't get this to work

In the past when it hasn’t worked, I’ve found that it’s because of another plugin basically taking over the oEmbed process so it never gets to work. The first way to test this would be to disable all plugins except for this one and see if it works. Then start reenabling them until it doesn’t work any more to see which one is causing the problem. Some themes might be grabby with the oEmbed as well.