The plugin fallback mechanism might need UI to allow people to disable it temporarily or permanently for a site, in order to make that website work. This is specially important during a test period where we want to measure how much people will use it, and then these controls might be kept permanently after a wider release. It needs to be able to: - deactivate plugin fallback for a particular page that is loaded (i.e., fix this once) - deactivate plugin fallback for a particular page/site/domain (TBD), always (i.e., fix this always for this page) Hopefully we can tie this to the already exisitng click-to-play UI

To my understanding, the plan of record right now is that the fallback mechanism itself won't need UI or be user controlled. What the user will control is the global or per-site CTA setting. The fallback mechanism will kick automatically based on heuristics, and it's likely that there still will be an about:config pref to configure it.