UserAgent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/62.0.3202.75 Safari/537.36

Example URL:
https://watch.nba.com/game/

Steps to reproduce the problem:
1. Load and log-in at http://www.nba.com/leaguepass/
2. Load any previous or live game
3. Chromecast game with tab mirror

What is the expected behavior?
The NBA game should be casted to the Chromecast television in native bitrate/quality from the NBA League Pass source, rather than screen mirrored/captured.

What went wrong?
Every time I attempt to use tab mirroring on the NBA League Pass website in Chrome versions 61, 62 (latest 62.0.3202.75), and 63 (latest Beta 63.0.3239.18), it is screen capturing/transcoding, resulting in mediocre video quality and buffering/latency.

I've noticed that this behavior has largely been resolved, occurring only occasionally (~25%), in Canary 64 (latest 64.0.3252.0), so it appears this issue is undergoing some progress/change. I can see the quality significantly improving with native casting from the NBA League Pass sources -- also the League Pass website is indicating the direct casting: see https://i.imgur.com/GADQGjD.jpg

I don't know if this is related to stream encryption/DRM by NBA League Pass, as I see the M3U8 file notes AES-128 is used

Does it occur on multiple sites: N/A

Is it a problem with a plugin? N/A 

Did this work before? N/A 

Does this work in other browsers? Yes

Chrome version: 62.0.3202.75  Channel: stable
OS Version: 10.0
Flash Version: