Generally speaking, you will have a lot of work to do to get one of those YouTube clones working properly:
No problem with all the above
You will need to make several PHP configuration changes to PHP to facilitate these settings, and some of those setting are too high/inappropriate for a shared server (though you could probably use them in a PS machine if you have allocated sufficient resources)
Of this list, you will need to install/configure everything listed in the way of software except GD2 - the FFMPEG pre-installed on the server is not likely to meet your needs due to it's configuration.
Np problem here as far as availability of functions, but our procwatch daemon will likely find, and kill, any background process that is run that uses too much CPU, RAM, or runs to long ... so it is quite possible that you will have problems with that.
--DreamHost Tech Support