It is a matter of checking out Meghan for yourself, freezing the frames and looking at how she is holding the chords. Let me categorically state, there is no A chord in the song. So those who think there is, go and get on your bike and take a long ride of a short pier, then watch the video for yourself while drying off with a big fluffy towel. For you will need the towel.

Here it is:
For some reason this chord does not come up on the chord finder, it actually is not a defined chord. Saying this, I guess if you know how to play music and it sounds good the music you play does not have to be dictated by text books. Maybe it's what makes Meghan's song sound great. I blew up this picture just to show what I mean.

YouTube videos are interpretations by those who post the videos of what are the true chords and beats of a song. I've got to understand this a lot more as I've checked more and more tutorials. There would be a favourite youtuber for me who seems to get it right but then they will do a version of a song and it just doesn't hit the spot. In which case I choose to move onto another person or even try a variation on the their interpretation so as to bring the chords or strum pattern closer to what I think the song sounds like.
When it comes down to it there is no right or wrong, there is only the method which gives you the most fun. Because it's all about the Bass, the Bass no Treble.