[docs] Improve documentation of dependencies

Related: #348

README.md

@@ -22,8 +22,8 @@ yt-dlp is a [youtube-dl](https://github.com/ytdl-org/youtube-dl) fork based on t
 * [NEW FEATURES](#new-features)
     * [Differences in default behavior](#differences-in-default-behavior)
 * [INSTALLATION](#installation)
-    * [Dependencies](#dependencies)
     * [Update](#update)
+    * [Dependencies](#dependencies)
     * [Compile](#compile)
 * [USAGE AND OPTIONS](#usage-and-options)
     * [General Options](#general-options)
@@ -166,16 +166,30 @@ sudo aria2c https://github.com/yt-dlp/yt-dlp/releases/latest/download/yt-dlp -o
 sudo chmod a+rx /usr/local/bin/yt-dlp
 ```
 
+### UPDATE
+You can use `yt-dlp -U` to update if you are using the provided release.
+If you are using `pip`, simply re-run the same command that was used to install the program.
+
 ### DEPENDENCIES
-Python versions 3.6+ (CPython and PyPy) are officially supported. Other versions and implementations may or maynot work correctly.
+Python versions 3.6+ (CPython and PyPy) are supported. Other versions and implementations may or may not work correctly.
 
-On windows, [Microsoft Visual C++ 2010 Redistributable Package (x86)](https://www.microsoft.com/en-us/download/details.aspx?id=26999) is also necessary to run yt-dlp. You probably already have this, but if the executable throws an error due to missing `MSVCR100.dll` you need to install it.
+<!-- https://www.microsoft.com/en-us/download/details.aspx?id=26999 -->
+On windows, [Microsoft Visual C++ 2010 SP1 Redistributable Package (x86)](https://download.microsoft.com/download/1/6/5/165255E7-1014-4D0A-B094-B6A430A6BFFC/vcredist_x86.exe) is also necessary to run yt-dlp. You probably already have this, but if the executable throws an error due to missing `MSVCR100.dll` you need to install it manually.
 
-Although there are no other required dependencies, `ffmpeg` and `ffprobe` are highly recommended. Other optional dependencies are `sponskrub`, `AtomicParsley`, `mutagen`, `pycryptodome`, `phantomjs` and any of the supported external downloaders. Note that the windows releases are already built with the python interpreter, mutagen and pycryptodome included.
+While all the other dependancies are optional, `ffmpeg` and `ffprobe` are highly recommended
+* [**ffmpeg** and **ffprobe**](https://www.ffmpeg.org) - Required for [merging seperate video and audio files](#format-selection) as well as for various [post-processing](#post-processing-options) tasks. Licence [depends on the build](https://www.ffmpeg.org/legal.html)
+* [**sponskrub**](https://github.com/faissaloo/SponSkrub) - For using the [sponskrub options](#sponskrub-sponsorblock-options). Licenced under [GPLv3+](https://github.com/faissaloo/SponSkrub/blob/master/LICENCE.md)
+* [**mutagen**](https://github.com/quodlibet/mutagen) - For embedding thumbnail in certain formats. Licenced under [GPLv2+](https://github.com/quodlibet/mutagen/blob/master/COPYING)
+* [**pycryptodome**](https://github.com/Legrandin/pycryptodome) - For decrypting various data. Licenced under [BSD2](https://github.com/Legrandin/pycryptodome/blob/master/LICENSE.rst)
+* [**AtomicParsley**](https://github.com/wez/atomicparsley) - For embedding thumbnail in mp4/m4a if mutagen is not present. Licenced under [GPLv2+](https://github.com/wez/atomicparsley/blob/master/COPYING)
+* [**rtmpdump**](http://rtmpdump.mplayerhq.hu) - For downloading `rtmp` streams. ffmpeg will be used as a fallback. Licenced under [GPLv2+](http://rtmpdump.mplayerhq.hu)
+* [**mplayer**](http://mplayerhq.hu/design7/info.html) or [**mpv**](https://mpv.io) - For downloading `rstp` streams. ffmpeg will be used as a fallback. Licenced under [GPLv2+](https://github.com/mpv-player/mpv/blob/master/Copyright)
+* [**phantomjs**](https://github.com/ariya/phantomjs) - Used in extractors where javascript needs to be run. Licenced under [BSD3](https://github.com/ariya/phantomjs/blob/master/LICENSE.BSD)
+* Any external downloader that you want to use with `--downloader`
 
-### UPDATE
+To use or redistribute the dependencies, you must agree to their respective licensing terms.
-You can use `yt-dlp -U` to update if you are using the provided release.
+
-If you are using `pip`, simply re-run the same command that was used to install the program.
+Note that the windows releases are already built with the python interpreter, mutagen and pycryptodome included.
 
 ### COMPILE