That's exactly what the creator of Stop Auto play for Youtube thought and decided to create this add-on for Google Chrome that pauses those videos opened in new windows.
When you decide to open video in a new tab, it automatically starts playing, but if you use Stop Autoplay for Youtube it will load but it will remain paused until you click the play button.
This is the perfect way to open as many videos as you want, have them loaded and play them whenever you want.
If you usually view videos or videoclips on Youtube, Stop Autoplay for Youtube will become one of your best add-ons for Chrome.
Google Chrome required.