You can not testfor scoreboard objectives with dashes, for example Test-X, with a commandblock and comperator, using "/testfor @a[score_<NAME>_min=5]", unless you update the commandblock as shown in the video.

Steps to update the commandblock:
Commandblock should output a signal for a value of Test-X of at least 2.

> Test value changes from 1 to 2
Commandblock is not updating / give a output signal
-> Change from "Always active" to "Needs redstone", click done, then change it back.
The commandblock is now giving a correct output

> Test value changes from 2 to 1, so the output should now be turned off, but it is not updating.
The steps from above are not working this time to update the commandblock output.
-> Change the commandblock to "Impulse" and then back to "Repeat"
The output is now turned off, as it should be.

However, this does not happen if the scoreboard objective is named normal, like "test" for example.
I only tested this issue with this dash: - and in Minecraft 1.9.4 as well as 16w21b. Both versions are affected by this issue, so i guess the versions 16w20a and 16w21a should be as well.

The video, by the way here is the link: https://www.youtube.com/watch?v=Gwc1Q95XtHc, was recorded in Minecraft 1.9.4.