There are lots of resources available online, some great and some really bad. One of the issues I have with YouTube videos is that I have found many of them are wannabe tutorial writers and they haven't yet found the right way to do things in Photoshop. This is simply a word of caution but there are also some good ones on their.
I have that the videos at Lynda.com are better than most out there. If you registered a legal copy of Photoshop you get the option of a gift and one of these is normally a complimentary 30 day Lynda membership. The other option would be to join NAPP, it has a large library of tutorials and its membership brings along a number of other benefits.
One thing that I learned early on in Photoshop was that it was so huge that you will probably never master the whole thing. Focus on what you want to learn and don't let yourself get overwhelmed by the sheer size and capabilities of what this program can do. I never took a course but have attended some one day seminars but more in the digital drawing arena than editing photos. You may find that a tutorial is not exactly what you are looking for but there is always something that you can pick up from these, whether it be a way of managing layers to using the brush tool. I spent innumerable hours watching video tutorials and that was what got me to where I am today. I am efficient, not great but I get the job done and do it non-destructively. If you take the time to learn at a decent pace you will be efficient in photo editing in a reasonable time frame.