Do you have a different USB port that you can connect to, to see if that make a difference?
Do you have any other video capture devices like an AJA or Blackmagic Design or similar?
Cheers Jeff, thanks for getting back to me.
I had no luck with changing the USB ports about. Nor do I have any other video capture devices connected.
However, I installed Character Animator on my old 2010 Macbook. (Surprised it ran, but it did woo hoo.) The inbuilt webcam worked no problems. I then plugged in the external Logitech Webcam C615 and voila! Same problem occurred as on my Mac Pro (ie Camera Busy). If I did 'switch to next cam' on the laptop, it flicked over to the inbuilt webcam and worked again no worries.
(NB I didn't try restarting the laptop with the C615 already plugged in because time.)
So it seems that there is a problem with using the external logitech webcam. I don't know why this would be, as it's not a cheapo webcam (was about $70 when I bought it a few years back, goes for around $40 now) and I've not had any issues with it before. I use it for video conferencing which I do extensively and tested it on both the laptop and the tower with Photobooth, Skype, Facetime and Messenger. No problems there.
I'll try and borrow a webcam or two from mates to see if it's affecting all external webcams or just this one. I don't want to purchase a new webcam unless I have to.
Any further suggestions now that we've at least narrowed the frame of reference a bit appreciated as always.
It's odd that it'd show "Camera Busy" if you're just switching it ot on your older MacBook. I'll need to check around here if we have that or a similar model, but the model number doesn't sound like something I've come across so far.
I'm assuming the camera works OK in QuickTime Player if you try to do a new movie recording?
Yes I've tested the webcam with Quicktime (which I hadn't thought to do before), and it records and works ok.
Unfortunately I haven't been able to locate a nearby buddy yet with a usb webcam to borrow to test it out. If I can't, then I might have to spend some $ on a cheapo one, just to see if that works.
I'm marking this as answered as the Character Animator team are looking into a solution.