Yes, you do need a BFO. See my other video "Crystal Radio 160m SSB Test". Right at the end you'll see I'm using an HP 8924c analyzer to generate the beat frequency. It is injected into the crystal radio tank circuit via the 10 turn coil on the left side of the coil form.
The "Band Shift" switch on the radio is just selecting different taps on the tank coil. I mainly use this with the AM broadcast band to shift the tuning of the variable capacitor toward the top end or bottom end of the broadcast band to make tuning stations at either end of the band a little easier.
