I'm having the same issue and I get a picture exactly like the one you posted. It says sign in to confirm you're not a bot, but clicking that does not open up a window to sign in.
In the past, I've right clicked that image and chose "copy url of the video," then pasted it into a new window and watch it on youtube, but it no longer allows that.
I never know when this will happen. Some days I get that, other days no. Sometimes I can log off the forum, clear browsing history, close all windows, then reoopen and log back into the forum. That does not always work. I've even tried explaining this bothersome issue in posts I've made elsewhere in the forum, and a few members have responded with suggestions, none of which have worked for me.
That is one reason, whenever I post a video, like a song, above the embedded link, I type the name of the song and the performer. That way, if anyone is having the same issue, but may be curious enough to want to hear it, they can open a new window and search for the song by name, and they can play it that way.