Fusion node issue

I'm unable to connect the nodes in the short movie below. I've watched a video on Youtube and he does it exactly like that and it connects. Why doesn't it work?

https://drive.google.com/file/d/1EGDbTL ... sp=sharing

Which video on youtube? Do you want to swap out current connection Background already has or what is the intent here?

Drop the output wire onto the input (triangle) you want to connect. Or hold alt while dropping onto the center of the node, and you'll get a pop-up asking which input to connect to (only one choice in this case, of course). Or if you're trying to create a Merge of the two nodes, you drop the wire on the output (square). If you're using the default settings, the drop target is pretty small, so it can be hard to hit, especially if there's a wire already connected, which seems to increase the chance of rejection. (That might be my imagination—I've never tested it, but it's been my impression for years.)

However, I think that the automatic Merge creation by dropping on outputs might not work for mask tools like Polygon. I'm not sure about that and don't have Fusion handy to check

Which video on youtube? Do you want to swap out current connection Background already has or what is the intent here?

This video.

I'm trying to figure out how to make a circle appear around a specific object in my movie. Like an animation you might say. I found this and other videos and I'm experimenting to learn how it works.

Drop the output wire onto the input (triangle) you want to connect. Or hold alt while dropping onto the center of the node, and you'll get a pop-up asking which input to connect to (only one choice in this case, of course). Or if you're trying to create a Merge of the two nodes, you drop the wire on the output (square). If you're using the default settings, the drop target is pretty small, so it can be hard to hit, especially if there's a wire already connected, which seems to increase the chance of rejection. (That might be my imagination—I've never tested it, but it's been my impression for years.)

However, I think that the automatic Merge creation by dropping on outputs might not work for mask tools like Polygon. I'm not sure about that and don't have Fusion handy to check

Thanks, Bryan!

Yes, I was trying to create a Merge. However, it seems as if I need two backgrounds like in the YT-video and connect the 2nd background to the 1st and then make a Merge from the Polygon1 to the 2nd background. With only one background I can connect it to Polygon1 by alt-dropping, with option 'Effect Mask'. But then the connection to MediaIn1 breaks. I suppose I need that connection too?