In conclusion, It does work sometimes, but it isn't as straightforward as it might be.
I think this is wrong. There are a few people on this forum that can do video calls to PCs with the built in software. Using a pure SIP environment.
Is this Gizmo specific? I didn't notice because over a generic SIP call it works PC-NIT no problem (if the SIP server supports video). Glad I did my own server....