Well done video, I am glad you had patience with it while you had trouble with full wallet. New separate single-address wallet is needed to be created only if you are old user of Byteball app, since January 2018, all new wallet installations come with single-wallet address by default and you have an option to make separate multi-address wallet if you wish.

If you want to to try out smart-contracts then easiest would be trying to bet on some sport event with Betting Bot. I made a website front-end for that bot, so it would be easier to navigate there. After you have decided to take a bet, it will offer you human-readable smart-contract to confirm. 6 hour after the event and if you won the bet, it will let you send the funds out of that smart-contract. It blew my mind when I first tried it.

Difference of private vs public Steem attestation is that with private option, you can save the attestation profile to your wallet (only hash is sent to DAG), but with public option, the attestation is saved in the DAG. If you do the private, then other bots need to ask you to share your attestation profile, but with public they can check it more easily. Also, others can use steem/teamhumble as an address to send you Bytes only if you picked public option. If you picked private on the first time, but want to enable it now, then you can do the attestation again with public option (no reward on second time), but you can't go from public back to private.

Also, make sure to do full backup because otherwise, if you loose access to your device or loose it, you won't be able to restore your attestation profiles and private assets like blackbytes.