No, mIRC is not a file sharing program despite popular belief. IRC means Internet Relay
Chat and is meant to be a means of communication between people. True to say part of that is sharing files, but not in the sense of MASS downloading ILLEGAL files.
Speaking of legality, downloading mp3s, movies, software, cracks and other warez is illegal. We do not help with it on these forums. mIRC is not one of these p2p programs that is meant for that kind of service. It is certainly possible that participation in this kind of activity using mIRC or any other program can lead to prosecution and huge fines. It has happened to inviduals and will happen again and probably more frequently.
As for 'safe', definitely not. Downloading files from mIRC with File Servers and XDCC bots etc. can often lead to being infected with a virus or trojan. It is a general rule that you should never accept files from people that you don't know, it's like taking sweets from a stranger or a car lift from a stranger - you just don't do it. Being infected can lead to others taking control of your computer, causing potentially huge damage to your computer and the possibility of causing your computer permanent, unfixable damage. Stealing passwords is not uncommon either.
You may wish to view
this post.
Regards,