I can imagine imagery in two different ways.

1. One way is the "behind the eyelids" technique, where the imagery seems to be
coming from the retina, or at least I experience it that way. I cannot
currently generate the high quality photographic imagery of the OP, and even
the experience of colour is pretty sketchy. That's today, awake, although
sometimes it gets better when I'm in bed and about to fall asleep. Either way,
this only works if my eyes are closed, or it's pitch dark. With my eyes open,
the signal from my retina washes out the image, which is very dim. One person
I met who experiences this calls the experience "phosphenes". The experience
doesn't look real, and I have no sense of depth or spatial location, like I do
with vision. It is only partially under conscious control. I get images, then
I "make suggestions" about what I want to see, and then it kind of drifts in
the direction of what I want.

2. The other way works with my eyes open. I can do 3D objects, even set up a
wire frame cube spinning around my head. The object can be "inside my mind"
with no defined location, or I can locate it in space. I barely have any colour
available in this subsystem, but that could be lack of practice. This is under
full conscious control. I have no difficulty distinguishing these images from what
I am seeing, I experience eyesight and these images as two different mental domains.

I just ran a test, and I can do both things at the same time, but it requires a lot of concentration and I'm not good at it.

I know from talking to people that there is a lot of variation in how people experience mental imagery.

Based on what I've read, LSD and psilocybin hallucinations may be be a more powerful version of "system 1" imagery as described above. That's because: at low doses, you can only see the hallucinations with your eyes closed, and they are only partially under conscious control. (There are instructions on the web on how to influence the imagery.)

UPDATE: I wondered whether my system 1 imagery is "in the retina" or "in the visual cortex". As an experiment, I stared at a bright light, then closed my eyes to see the retinal afterimage of the bright light. Everybody gets these afterimages. Then, I was able to modify the afterimage! After some work, I eventually changed the colour of the afterimage and made it into the centre of a flower. To my delight, the flower had an almost photographic quality. This doesn't really prove anything about retina vs visual cortex. But this is a better result than I've had in the past, before I read the ideas in this post.

Finally, the OP and video describes "image streaming", which seems to be a more advanced version of what I do when I try to shape a system 1 "retinal" image. Afterimages are one way to produce a seed image. In the past I've just created images starting from a black visual field, but I guess it's easier if you start with a seed. Apparently if you get really good then you can have full conscious control over system 1 mental imagery! I had not previously considered talking out loud to influence the image.

Now I'm wondering whether "microdosing", a Silicon valley practice that has been discussed on HN before, would improve your ability to perform "image streaming". Maybe other people with more knowledge of this can comment.