What is 'vision externally' in AN8.66? In AN 8.66 the Buddha says, &quot;Not perceiving form internally, they see visions externally. This is the second liberation&quot;.
I am totally confused here. If by 'form' we mean body, how not to perceive it internally. And what is meant by 'see visions externally'?
First thing, you shouldn't be relying on B. Sujato's translation for meditation specific terms. He has gross misunderstandings of key words like kāya (physical body), rūpa (in meditation context, usually means 4 elements of physical body of meditator). So in his translation, he inconsistently translates rupa sometimes as 'physical form', sometimes as 'vision', according to his wrong understanding of jhana and arupa samadhi.
Going by a straightforward, and correct EBT interpretation, 'rupa' translates consistently as 'physical form of  the anatomical body made up of 4 elements and 6 sense bases active - you can see, hear, touch, etc.'
So the first base of liberation (vimutti), having form (rupa) and seeing form is referring to the point of view of being in the 4 jhanas, where the 6 sense bases of the physical body are active.
The second base of liberation, one is in an a-rupa (form-less) samadhi attainment, you are in a meditative state where you can't perceive your own physical form of body anymore, can't hear sounds, 6 sense bases are divorced from the mind. But you can perceive external forms, for example seeing visions of the rupa (form, 4 elements) of external world, other beings, etc.