to review a proper ssl configuration of your https-webserver, try ssllabs or Security Headers.

streaming to chromecast is not possible with mkv-videos, so i had to convert them.

easy done:
for i in *mkv; do ffmpeg -i "$i" -acodec aac -vcodec h264 -strict -2 "${i%.mkv}.mp4" && rm "$i"; done;
will do it…