Just a heads up, you wont be able to play TF2 in secure mode with any client side plugin unless valve signs it. There isn't really a special way to get this done, I believe the guy that made prec just emailed valve. if you want to test in insecure mode just use -insecure as a launch option.

Maybe it isnt an option, but boot camping to windows is probably the easiest. TF2 will typically run better as well. As for API their is the steam developer wiki which should contain everything you need.

can't vouch for it (never tried it): [MAC] An alternative to P-REC it's a script, rather than a plugin, and i believe it starts recording a new demo every time you switch classes. it's the only 'p-rec for mac' i've ever come across, though. maybe this is as good as it gets for you. edit: i realise it's not perfect, but since(if) there is no p-rec-like plugin for mac, you might as well use it. personally i'd suggest you make a script, optionally based on this one, which binds a button to start recording a new demo.