What you trying to do is definitely possible, I attached an example of a creative that includes a YouTube video component and custom controllers.
Here how you can proceed for recreating the same ad.
From the component menu, drag and drop the YT video component into the stage, after selecting it from the strage, from the Properties panel, under Controls select None from the drop down menu.
Now, create 4 tapAreas on the stage and name them something along the line of the controller you want to implement ie. PlayTapArea, PauseTapArea, ReplayTapArea and ToggleMuteTapArea.
Now select the PlayTapArea, and from the Events panel press the Plus Icon. From the list of possible Target select PlayTapArea, from Event select Mouse->Click, from Action select YouTube->Play after Pause, and finally from Receiver select the name of the youtube video component (if you didn't change it is probably gwd-youtube_1.
You have linked the click on the tap area to the behavior desired.
Do the same for the other 3 tap areas and you have done.
Please let me know how it goes!
Nicola
Regarding the "hide/show button" animation that you are trying to achieve, that can be done by using another event. The Event would be again based on the click, but this time you want to select from ACTION css-> set style, and as target you should select the button you want to hide/show. Use the css property display: block or display:none to accomplish the change of visibility.
Hope it helps.