I have my own Youtube channel for quite a while now, where I upload my recorded games https://www.youtube.com/user/MetaverseMachinima/videos?flow=grid&view=1
I started upload my vids at 1080p (16:9) using Fraps, which were recorded into a 1 TB WD green series. So I really don´t know why you can only record in 360p.
Recently I took a Samsung 830 128 GB SSD, and I am using it now to record my games. I run the games from the SSD, and also record the vids into it. There is an improvement of course, but my 1 TB WD green series wasn´t that bad doing the same job.
I´d recommend you to get the Samsung 830 128gb for 80€ -- it is not just about boot time -- it will improve the general performance of your PC, to include recording games.
You really don´t need to get a WD velociraptor, if your intention is to record your games. Just get the SSD and record your games into it.
There should have an issue that prevents you from recording your games at 1080p, but it isn´t your HDD.