Following things are logged on page load in a webview browser:

cast.js:7 Uncaught ReferenceError: chrome is not defined(…)
video.js:21317 VIDEOJS: ERROR: TypeError: Cannot read property 'progressControl' of undefined(…)

It never gets to setting the src attr on the video tag - it seems like this site is just stumbling over a difference between the js environment that chrome makes available, and that of webview. Unfortunately it's very hard to work out where the divergence is. Without more information it's hard to say if webview can do anything about this.

Is this a regression from m54?

No feedback was received in the last 30 days from reporter "carlos@instantbits.com", so archiving this. Please re-open or file a new bug if this is still an issue.

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot

Was the question on comment #2 for me?

Yes. When reporting bugs on the beta version it's really useful to know whether it's a new issue in the beta or whether it already existed in previous versions. As Toby noted, it looks like the page here is just expecting Chrome-specific JS properties to be available that aren't there in WebView.

I don't know how to get m54 but I can tell you it doesn't work on android 4.4 either so my guess is that it hasn't worked for a long time. Thanks. 

Then this looks like a problem with the site, not with WebView.

You are probably right, thanks.