activateControls = function(){
    if (player.controls() && !player.usingNativeControls()) {
      tech.addControlsListeners();
    }
  }
Set up click and touch listeners for the playback element
On desktops, a click on the video itself will toggle playback,
on a mobile device a click on the video toggles controls.
(toggling controls is done by toggling the user state between active and
inactive)

A tap can signal that a user has become active, or has become inactive
e.g. a quick tap on an iPhone movie should reveal the controls. Another
quick tap should hide them again (signaling the user is in an inactive
viewing state)

In addition to this, we still want the user to be considered inactive after
a few seconds of inactivity.

Note: the only part of iOS interaction we can't mimic with this setup
is a touch and hold on the video element counting as activity in order to
keep the controls showing, but that shouldn't be an issue. A touch and hold on
any controls will still keep the user active