I haven't flown with DD since before she turned 1, but I guess it's the same premise as a long car ride. We find what works best is to hold off on things like DVDs until she gets restless, otherwise she gets restless far quicker because the novelty wears off. Also getting her some new things. A new book or toy, a new colouring book. Because she hasn't seen them before, the fun factor sticks around for longer. Stamps and a notepad or a sticker book also could work well.