@Clusterfrog; If you use safari browser I recommend you to try out the ‘click to flash’ extension, it gives you total control of the flash elements and load only on your command you find it here; https://extensions.apple.com/
It have options so the flash elements runs like you want, HTLM5 or quicktime player ++, and have auto native fall back option if that fails, it also let you download contents on YouTube and on other video sites, its easy to use but you need to set it up so it works for you…then you can surf without annoying flash popping up and banners playing before you tell(‘click’) them to