SCCM 2012 R2 How to Configure PXE Boot on DP and OSD Checklist
These checks can be made before doing Any PXE related lab for example OSD or Migration, Capture and Deploy.
I forgot to add Network Access Account check in the video so here are the steps to do that.
Check the Network Access Account Setting
To configure the Network Access Account, open the CM2012 R2 console, click on Administration, expand Overview, expand Site Configuration, click Sites, on the top ribbon click Configure Site Components, click Software Distribution.
Click on the tab Network Access Account, choose Specify the account that accesses network locations (by default the option is set to Use the computer account of Configuration Manager client). Click on the orange icon and add the user account that enough permissions to access the content which is required while deploying Operating System.