Allows to adjust thresholds which control the video quality level
in the thumbnail view.

Changes the default behaviour to request the SD (360p) resolution only
when the thumbnails are at least 360 pixels tall and the height of
720 is required for the high quality level.

The thresholds can be configured with the 'videoQuality.minHeightForQualityLvl'
config property. Check the description in the config.js for more details.