Originally Posted by
JimInOhio
In addition to the helpful post above mine, you might find it faster and more straightforward to not go through security right after checkin but instead walk outdoors from TBIT to T7 and then go through security there. Returning to TBIT airside as the video outlines would be fastest.
Second this. Did it recently for a BR flight and it was painless. Security at T7 is almost always better than security at TBIT too.