This functionality is intended to eventually encompass the current format filtering.
Just checks that the 'keepvideo' option works as intended.
In preparation for #4822, extend jsinterp by a lot. (We may even have to/want to write a proper interpreter with actual parsing)
We now test for the age_limit being set right in test_download, so we don't need more than two tests for the actual age limit handling.
They have a manually uploaded subtitles track and YouTube can transtale it.
This is now covered by every single test_download testcase anyways :)
From now on, the line from __future__ import unicode_literals should be contained in every single Python file lest we run into any more 2.x/3.x issues. Going forward, we're likely to develop on 3.x only and would likely miss subtle bugs otherwise.
Reported at https://news.ycombinator.com/item?id=8648121