In answer to your questions:
1. This is a default function of the theme, so it would require customization on your part if you were looking to remove the functionality altogether. Our themes are not encrypted, so you are free to make modifications if you wish.
2.
HireBee is now Escrow ready:
For each agreed project you can hold the money until work ends (via PayPal Adaptive Payments). On completed projects, the money held in escrow minus any site commissions will be automatically transferred to the freelancer. On non completed projects, employers are automatically refunded
3. You can prevent registration on the site, but there is no registration moderation as such. This would either need to be done manually, or potentially you may be able to customize or find a plugin for this purpose.
4. There's no specific field for this, or upload option, so you'd likely need to look at using embedded YouTube code or simply a link. Thanks.