* [youtube] Fix thumbnail URL
* [youtube] Parse API parameters from initial webpage by [colethedj](https://github.com/colethedj)
* [youtube] Extract comments' approximate timestamp by [colethedj](https://github.com/colethedj)
-* [youtube] Fix `\_extract_alerts`
+* [youtube] Fix alert extraction
* [bilibili] Fix uploader
* [utils] Add `datetime_from_str` and `datetime_add_months` by [colethedj](https://github.com/colethedj)
* Run some `postprocessors` before actual download