Assuming you have Python installed, you can use getyoutubecc, which is a Python script.
Execution is as follows
>> python getyoutubecc Akqkvx407c8
Then keep the video and .srt in the same folder and you should be able to play in VLC.
For a non-technical way try one of the conversion sites such as http://mo.dbxdb.com/, which will download the .srt within a zip.
Select the track from the zip file
And then you should see the subtitles appear
For videos with multiple tracks you will have to dig in and save it from .xml to .srt manually, there isn't a ready made tool out there on the web
Where can be
en for English,
it for Italian and
de for German.
<VIDEOID> is the id of your Youtube video.
For some videos, it appears necessary to specify the name of the subtitle track, as seen on the Youtube page of the video, as a third argument: