Extract text/string from URL text

[CherMeow]

So I need some help here...
I have columns A to G like this:

I have a query code in A1 which retrieves some data from other spreadsheet in other tab:
=query('A spreadsheet'!A:T,"select F, B where (T = 'Yes') and F != '' label F 'url1', B 'special code'")

The code works fine everything works.
But the question is, I want to retrieve the text after the "/" in url1
So like this..
From ht..tp//youtu.be/8tMq70b0Ork
To
8tMq70b0Ork
So what I need is to remove the "...//youtu.be/"

What do i do? Is there any way to combine the formula needed for that with the query code I have above?
Because I need to do this for many rows and cells not just a cell.

Thank you.

[CK76]

If "ht..tp//youtu.be/" is constant...

You can use SUBSTITUTE.
=SUBSTITUTE(YourUDF,"ht..tp//youtu.be/","")

If it isn't constant, and you want portion after last "/".
=TRIM(RIGHT(SUBSTITUTE(YourUDF,"/",REPT(" ",99)),99))