Outside of what is in my video. I want to point out a few more pieces of information.
If an exchange converts KOIN to VHP, similar to how HIVE can be powered up, the exchange would need to run a node in order to cast votes. It is possible that exchanges will run their own mining node and offer mining services to their users. This would mean that exchange would burn KOIN at the request of their users and use that VHP to do things such as vote in governance. The exchange may employ a time lock, preventing users from withdrawing their VHP from the exchange. Remember that without VHP, the node cannot cast a vote, and on top of that, only the blocks that the exchange produce would have their vote. To combat this, users should use decentralized burn pools such as burnkoin.com (which i am cofounder of) or fogata.io (which another HIVE developer has created). This is a better model and we're constantly striving to make things better.
This is going to be my favorite topic. you are 100% right that if you lose your key, you lose your account. Because Koinos drops the concept of EOAs, every wallet can natively support smart contracts, which means that we can provide tools such as account recovery through smart contracts rather than creating them at the system level like HIVE does. This simple feature (allowing all wallets to support smart contracts) is the basis for Koinos Account Protocol, or KAP (see more at https://kap.domains). I am a co-founder of KAP as well and we took into consideration, the benefits of HIVE's account system when designing it.