RC-505 Auto record

[HSilinski]

Just bought a used RC505, coming from a Digitech jam man stereo. Love everything about 505 except can not figure a way to auto record, start recording upon detection of input. This person seems to have found a way by creating a blank track, but not sure I understand how that helps / works. Thanks in advance :) https://www.youtube.com/watch?v=zFDgAEO2Auk