[bug] Browser video playback had issues after a second or so

In some cases, in two websites other than YouTube, Sailfish OS browser had the following issues after a second or so of successful playback: 1.- Only a small area of the video frames is displayed. 2.- Video playing speed is decreased. I tried this on Sony Xperia X (Rokua) and on Jolla "1" (Nuuksio). URLs: 1.- [https://edition.cnn.com/videos/business/2020/05/06/stores-reopen-economic-restart-restaurants-closed-travel-recovery-orig.cnn-business/video/playlists/business-coronavirus/](https://edition.cnn.com/videos/business/2020/05/06/stores-reopen-economic-restart-restaurants-closed-travel-recovery-orig.cnn-business/video/playlists/business-coronavirus/) 2.- [https://twitter.com/Claudiashein/status/1261739355024101377](https://twitter.com/Claudiashein/status/1261739355024101377) (I didn't sign in Twitter) Interestingly in this case video playback speed was not decreased (maybe it has to do with bitrate since this video is made of slides only): [https://twitter.com/CNNArgentina/status/1260724077058277377](https://twitter.com/CNNArgentina/status/1260724077058277377) I've opened [an issue](https://github.com/sailfishos/sailfish-browser/issues/675) on GitHub about this.