Use some scientific method to figure out which, if you can adjust the tire from side to side, then the bearings are loose or maybe your axle is bad (manufactured to low tolerances)
take the wheel off and let the forks sit on somthing solid. slowly and lightly raise/lower/fiddle with the handle bars, not at all like how you did in the vid, make sure the fork lowers remain on the surface. If there is movement, but the fork lowers remain on the surface, then the headset is loose.
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