As always, everything - and I mean EVERYTHING - in these videos is subject to individual/personal interpretation. Clearly, none of us know what happened that night, but it never hurts to speculate.
I strongly believe that white guy had A LOT to do with her disappearance. His body language, to me, screams perp. But, it's also crossed my mind that "oh, maybe he didn't want to be in the way" or "oh maybe he didn't want to be obvious in checking out a group that was harassing her" or "oh maybe he didn't want to walk and text."
What makes me most uncomfortable is how soon after she walks by he leaves. He cuts in front of the group of guys - so, "getting out of the way," to me, is not an option. He *watches* her, IMO. And then, to top it off, he's STILL behind her, one video over (Tuel's). For him to pawn this off on some random guy is unbelievable. BS you figured she knew the guy and you left it alone. Clearly, if you were "concerned" enough, you wouldn't have hidden in between umbrellas, and then got on her heels the moment she passed by.
But like I said, we all have different opinions, and they're all welcome.