The National Gallery has a good YouTube channel, with talks about paintings, discussions about exhibitions and behind the scenes looks. A good series for the season is called Gold, and one episode looks at how the framing department works. The gallery has a lot of frames to take care of, and many are very ornate with a lot of embossed gold to them. It also has a mention for one of the largest and most ornately framed paintings the gallery has, the painting The Raising of Lazarus.