Thanks Pagano! Unfortunately there are a few more problems. So, I've downloaded the pdp library. There aren't inside it any patches with the names pdp_mgrid or pdp _qt ( I found only pdp_qt_control). I searched to the internet and I found the pdp_mgrid and pdp_qt-help. When I open them there is a box to each one, marked red (missing/error command). The boxes have the commands [pdp_help_output], [pdp_spigot]. I searched in the internet if there is another library that I should install but I didn't find anything. For the y_qt I didn't find anything at all! Any advice for what should I do? Moreover, how can I view a video manipulated by a pdp chain? When I connect it somewhere like the [pix_texture] and [rectangle 4 3], I get errors. Is the pdp chain just for manipulation? If that is so, when I connect different parts directly with [pix_film] I get a white screen.