Hopefully the app uses something less power-hungry than JS and a web browser to render the video. Ideally we wouldn't be using those for that task anywhere else

Hopefully the app uses something less power-hungry than JS and a web browser to render the video. Ideally we wouldn't be using those for that task anywhere else either, but that battle's been lost. Also: if they make you install an app they can track you better, and make it harder to block their ads/spying.