I think it's more online videos than on hand experience behind point of sale
Online training provided
Depends, the training for seasonal staff seems pretty poor. They usually have them attend a group induction and provide some training. Not everyone learns to use the cash register at christmas the more 'fun' jobs are usually reserved for more senior staff.
If you're hired outside peek trading seasons the training is better. I was fortunate to be inducted one on one with my manager. You can expect a large majority of your 'training' to come informally from the senior casuals, ask them how stuff works and how they do things. I've worked at a few stores now and this seems to be the best way to get good at the job.
Training is average.
Very good training
The people who gave the training training for that