Fedora 25, Intel Corporation HD Graphics 520 (rev 07)
When adjusting the settings in the encoding section of the properties window, you have the option to use presets for Output Quality. When these presets are selected, the various video encoding bitrate settings are grayed out and may not be adjusted. It is not clear to the end user that the only way to adjust those settings is to go back to Output Quality and select "None; use constant bit-rate". This is also misleading because the bit rate settings don't have to be constant (eg: max/min).
It would be useful if, when using something other than "none" for the Output Quality, hovering over any of the grayed/unselectable fields in the bitrate area would indicate via a tooltip/hover that "You should select 'none...' in the output quality if you want manual control over bitrates".