My children often hangout at YouTube. They like watching movies, cartoon episodes, music videos, origami tutorials and even toy advertisements. As there are many positive things you can watch at YouTube, there are some videos that are generally rude and so “not appropriate” for children. And this is the reason why I don’t want them using the PC where I couldn’t see them. I want the monitor to be visible all the time.
Anyway, uploading toy advertisements are definitely one of the smartest things toy manufacturers ever did. My children would often time asks me to buy them the toys they see on YouTube just like the dolls wearing medical scrubs. They want to play doctor-doctor and hospital staff anytime. Another toy is the one that create real food. They felt like baking is just like playing.