Delete a Message
PrintScreen key is not the best way to make captures anyway 
For Youtube, the best solution is to get the file using JDownloader or http://www.bestvideodownloader.com/ for example (I use their Firefox Add-On)
This allows to get the highest quality available.
Once you have the file you can make captures with the programs mentioned previously (MPC-HC or VLC for example).
For Youtube, the best solution is to get the file using JDownloader or http://www.bestvideodownloader.com/ for example (I use their Firefox Add-On)
This allows to get the highest quality available.
Once you have the file you can make captures with the programs mentioned previously (MPC-HC or VLC for example).