Media Playback Percentage is included as a trigger (which uses the UA Video events tag.)

[KZeni]

I looked to propose this as a pull request, but the triggerId of my export didn't match up anymore.

                "name": "Media Playback Percentage",
                "type": "CUSTOM_EVENT",
                "customEventFilter": [
                    {
                        "type": "EQUALS",
                        "parameter": [
                            {
                                "type": "TEMPLATE",
                                "key": "arg0",
                                "value": "{{_event}}"
                            },
                            {
                                "type": "TEMPLATE",
                                "key": "arg1",
                                "value": "gtm4wp.mediaPlaybackPercentage"
                            }
                        ]
                    }
                ],

is effectively the trigger details (gtm4wp.mediaPlaybackPercentage being the important element here per GTM4WP.) I then attached this to the pre-existing UA Video events tag since its setup is just as fitting for the percentage as it is for the state change.

I'm thinking it would be a worthwhile addition to this since GTM4WP already has this while this container doesn't have it implemented yet.