Amelia said:
but I do know my youtube account was closed before the guy whose video I mirrored got his closed so I do think certain of us get "marked" and are subsequently watched more closely than others.
It's highly unlikely the WTBTS files takedowns manually (i.e. after finding a video), as YouTube has automated the process to look for copyright violations (process is called Content ID). What happens is content owners (Viacom, NBC Universal, etc) provides videos which they own for YT to load into their servers, and they periodically automatically look thru uploaded videos looking for "fingerprints" (characteristic) electronic signals that indicate someone uploaded their stuff.
Some users have attempted to edit the video to make it undetectable to the Content ID system (i.e. by changing pitch of audio track, or tweaking images, etc), but it's not for novices.