My ESC says No BEC , how does this affect my build

BEC   Battery elimination circuit 

The BEC is usually built into the Electronic Speed Controller (ESC),  it eliminates the need for a separate battery to power the 5V electronic devices.

If you have ESC without the BEC   you can use an external Battery elimination circuit 

This brings us to UBEC  
This is a separate component and is more efficient, more reliable than BEC as part of the Electronic Speed Controller

Why would a advertisement say   "80A UBEC 2-6S ESC Electric Speed Controller"  because Most BEC's  are linear type, and UBEC are switching type

It comes down to the  voltage regulator type

linear regulator  (BEC) and switching voltage regulator (UBEC)

Linear type   Highly inefficient and generates alot of heat, The primary reason people use them is because of  the lack of radio frequency interference that is common in
                     the switching type regulator  

Switching type  very efficient almost 85% efficiency  

The problem is this method emits loads of radio frequency interference and this causes unwanted issues with other electronic components 

Video transmission problems for one,  frequencies emitted by the switching voltage regulator interferes with the analog video signal and can reduce the range of the video. 

Here is a picture of a seperate BEC setup  This removes the power supplied from the ESC