Greetings Demetrio,
You’ve added an interesting contribution for sure. The concept of the “umwelt” (translated as “self-centered world”) would be somewhat analogous to the sensory aspect of the Markov blanket as used by Solms and Friston in The Hidden Spring: A Journey to the Source of Consciousness. A great read in my opinion but the free energy principle can be somewhat tough to really wrap your head around at first.
I enjoyed the video but the title is rather misleading. The speaker does not introduce anything close to a “new sense,” or even faint potential for a new sense, as the information being processed (regardless of its source) is still being processed through existing senses (in the video mostly haptic/mechanosensory.) By his broad usage of “sense,” we would have to say that any new piece of perceptible information holds the potential to be described as a “new sense” which seems rather ridiculous.
To address your thoughtful points though: “I think your writing takes for granted that we all agree on the definition of “reality”. According to what I read, my impression is that you define reality as the set of entities that can be described through objective measurements. At this point, I would like to suggest you next video because of the term “Umwelt”, which I found super interesting.”
I think that alone, “reality” doesn’t clearly speak to the either objective or subjective reality. One needs to be a bit more clear on how they are using the term. Many philosophers would use the term “objective reality” to refer to anything that exists as it is independent of any conscious awareness of it (via perception, thought, etc.) Subjective reality would then include anything depending upon some (broadly construed) conscious awareness of it “existing.” Particular instances of colors and sounds (as they are perceived) are prime examples of things that exist only when there are appropriate conscious states. Particular instances of emotions (e.g., my present happiness) also seem to be a subjective reality, existing when one feels them, and ceasing to exist when one’s mood changes. Simply speaking, the subjective reality is characterized primarily by perceiving mind. The objective is characterized primarily by physical extension in space and time.
To further explain the difference, the nature of an objective reality can hold significant influences over the perceptions that produce the subjective reality. However, t’s never the other way around so that subjective perceptions influence objective reality. For example, an ant’s inability to perceive a rock falling onto it does not dictate that the rock does not objectively exist and therefore cannot harm the ant.
You will find in my writings I do not chuck out the term “reality” without a supporting framework to clarify what, or which type of reality I am referring to. The fact that you point out that I may only be deploying only one usage (which you clearly define) demonstrates that you did encounter the supporting framework so much so that you were able to make any observation about my focus or usage. 
