Hey Exyle,
thanks for this video. I also live in the Netherlands and I had the same question about Steem. My take on it is as follows.
Steem is created out of 'thin air' - essentially, just like BTC - even though the technicalities are different. But still it's something out of nothing that is created. With that said, as far as tax ruling goes, I apply to it the same logic as they apply to BTC - at least at the time of writing this, when we have no other rules than the ones you mentioned.
We have to wait for the tax legislators to figure it out how to deal with this situation. Trying to figure it out by ourselves is basically being in their business - and that's none of our business so to say. So I just let them do their work and I follow the existing rules for the time being.
Even when they come up with a new rule, how far back can they make it retroactive? Perhaps it's good to look at some historical cases in the Netherlands as to how far back retrocativity of new rules typically applied.
Netherlands is a tax heaven when it comes to paying taxes on capital gains :) So, I'll gladly put aside 1.3% of my ROI from all cryptos - so far it's not an issue for me though :)))
Question - do you include your Steem earnings in quarterly taxes, too? Because I'm about to do them for Q4 2017
And last but not least, because cryptocurrencies are so puzzling for the current taxation system, I think the whole system will need to change and enter a new paradigm. This may take some time but until then, let's just pay our taxes on capital gains and invest wisely into something that can create a nice cashfow - in or outside of crypto :)