I am trying to play along toand standard tuning isn't quite matching up... so it must be down tuned a bit, but how much? I have the Snark SN-8 Super Tight All Instrument Tuner and I haven't used it to its full extent yet
Here are two methods to match your guitar to the video: one way with the tuner (using the 40-cent adjustment cited in the OP) and one without the tuner.
Recalibrating the tuner
According to the SN-8 user manual, to change the pitch calibration, one should
push the round "PITCH CAL" button on the back side of the tuner and immediately press either the up or down triangular buttons to choose a new tuning reference. The pitch reference can be set anywhere from 415 - 466Hz. Pressing the power switch on the front of the tuner resets the tuner to A-440.
Tuning 440Hz down by 40 cents gives gives 430Hz.
Not using the tuner
Tune any of the pitches you're certain of against the recording, preferably an open string. Then tune the rest of the guitar from there.