http://www.youtube.com/user/OrchestrationOnline
I have been following this man's videos for quite a while now, but he had stopped posting for a very long time, and his videos were targeting very much beginners to start with (as expected). He recently started posting again, he has upped the level, and I think some people here might find what he has to say very interesting, and I believe that a lot of other people (you know who you are, I do anyway) simply ought to pay close attention to him and what he has to say. Plus, he is one of the leaders on the bandwagon to save Sibelius, if that's your notator of choice.
Now, as good as his presentation is, one cannot learn orchestration by looking at a 10'-video a month, and should save money from buying execrable ready-made "music" software, and instead engage a proper musician privately, in order to learn this beautiful craft of tone-combination, which isn't placing one's hands on the keys of a controller-keyboard in octaves and getting a "finished" (but unsubtle) orkestral chord from the software.
This Thomas Goss guy is gauging the interest he generates from 'Like's on his videos, but I believe there are tons of people out there - like me - who don't have a YouTube account and don't wish to get one, so if you find what he does useful, 'Like' it, so that he continues his good work.
