What is the usage of "seeing that"?

[mokbon]

Hello:D

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You never actually stood there and looked up at that beautiful ceiling. Seeing that.
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-Good Will Hunting

What words are omitted? Is this right?
(I was) seeing that

Can I use like verb + ing as remembering something?

[probus]

It is a misquotation. That's why you are having trouble.

The actual line is:

"You've never actually stood there and looked up at that beautiful ceiling; seen that."

To clarify the meaning one could say that "you've never actually" has been
omitted after the semicolon and before "seen that", but it reads fine as it is. A fluent speaker would understand it.

[mokbon]

To clarify the meaning one could that "you've never actually" has been
omitted after the semicolon and before "seen that", but it reads fine as it is. A fluent speaker would understand it.

Thanks for help
However, I still don't know the reason he says like that...

[probus]

You can find the whole passage here:

Good Will Hunting (1997) - Memorable quotes

When you see it in writing you may find it easier to follow. Sean says that in spite of Will's extensive academic knowledge, Will lacks emotional experience and therefore lacks empathy and understanding.

If you are asking why the writer shortened it to just "seen that", a brief answer is that film dialogue has to move along quickly in order to be interesting and sound natural.

[mokbon]

Thanks again,

I mean when I say "seen that"?

What does he see exactly?

[JMurray]

I mean when I say "seen that"? What does he see exactly?

Thanks probus for the link. This is what Sean is saying:
Even though you may have read a lot of books about Michelangelo and know a great many facts about his life and work, you've never actually stood in the Sistine Chapel, taken in its ambience and looked up and seen that beautiful ceiling.