Thanks for the video. Have a lab tomorrow and will be using this information. You basically did my lab for me. I feel very confident I can do this now.
When you don't know the melting point range, you could try a fast (5-10 degree per minute) heat ramp from a low temperature (maybe 75 degrees) to a high temperature (maybe 250 degrees). There's not really a perfect way to do it. A better alternative might be to use a different analytical tool (IR, 1H NMR, etc.) first to narrow your range.