Alone's

It means that he thinks that the video is one of the best versions (plural) of the song You'll Never Walk Alone and that the victory exemplified the meaning of the song.
I'm not sure if the apostrophe is correct.

It's not correct. There is no plural apostrophe, that's a common error.

And he's talking about the exuberance of the crowd, not necessarily the quality of the singing.

The Scousers overturned a 3-0 deficit to qualify for the finals of the Champions League.

It's a really big deal.

It means:

... put out one of the best versions of You’ll Never Walk Alone ...

A poet buddy wrote a poem with the lines -

I wish all could win
Again and again

I wanted Barcelona to win, and Ajax for that matter.