Very interesting question. HTML5 audio and video are definitely a possibility, if there's a strong use case. If you have a specific idea, I'd be interested to hear it.
I don't expect Flash or Java support. Flash and Java apps that load their data from standard HTTP resources can be scraped regardless of support, the others need reverse engineering anyway and wouldn't fit with HTML scraping.
I use phantomjs as a headless audio player by loading youtube/soundcloud playlists and letting it play, but there is no official flash support on phantomjs anymore.
Sorry if you were expecting some novel idea, but it's just me trying to use a measuring tape to drive a screw.
I don't expect Flash or Java support. Flash and Java apps that load their data from standard HTTP resources can be scraped regardless of support, the others need reverse engineering anyway and wouldn't fit with HTML scraping.