Try printing ( with log) the command you are trying to execute, run it in a seperate command line to see if it's working properly.
since it's related to input I am suspecting the problem is with the youtube url you are providing
As already stated, 2000 http client threads. 2000 browser threads would be quite an intensive operation to say the least... You would need a very powerful vps with lots of RAM, but even then I'm not sure BAS would handle it without crashing.
