Update video compression scripts

aliases

@@ -510,6 +510,10 @@ dl_twitch_chat() {
 # using the full path to the cookies file, e.g.
 #   `tw-1080p60 <url> --cookies /c/<cookie_path>/twitch_cookies.txt`
 #
+# To extract a portion of a video, you have to first download the entire file and then
+# pass these args to ffmpeg: `-ss HH:MM:SS : start time to take`, `-to HH:MM:SS : end time`.
+# Or use the script `compress-video-portion`
+#
 dl_twitch_vid() {
     local format="$1"
     local shortname="$2"