The reality of the question of whether you require a licence or not boils down to one thing - method of delivery.
This came about through David Cameron's government acting to pre-empt companies like SKY who were agitating for BBC-free subscription services so their customers would not have to pay the licence fee.
Cameron's government amended the act so that any supplier of a live TV service in the UK must include BBC programming as part of their service, so, if you can get live TV, you can receive BBC, and you require a licence.
The language in the act is unambiguous and very specific. It states that you require a licence if 'you watch, or intend to watch'. This is to make it clear that you do not require a licence simply because you own relevant equipment, but that you must be in receipt of the ability to watch live BBC transmissions, or use iplayer, and actively do so OR intend to do so.
What it really boils down to, is that if you watch any sort of live TV where BBC is also available through the same service, then you require a licence. If you are watching a streamed service, or a broadcast on something like YouTube that does not also offer the BBC service, then you do not require a licence.