The landmine RDL is a great way to develop the adequate balance and proprioceptive control to transition from a normal double leg RDL to a true single leg RDL. The single leg RDL (which we will cover tomorrow) is particularly challenging for many because of the inherent BALANCE required to pull it off. If you're having trouble balancing during the single leg RDL, then this landmine variation will be perfect for you.
Because the bar with the landmine travels in a fixed arc, you don't have to worry about proper arm positioning like with a dumbbell or barbell. Furthermore, you can reap the benefits of offset contralateral loading without worrying too much about balance as you are still "fixed" to a stable-ish surface (ie the landmine).
The landmine RDL can either be performed with the landmine directly in front (left video) or perpendicular (right video). Personally, I like the perpendicular configuration because it induces a greater anti-rotation component to the exercise. You must increase you glute recruitment and force your hip external rotators to fire HARDER to keep the exercise motion purely in the sagittal plane.
If you don't have a landmine at your gym, simply place it at the corner of a gym (use a towel to prevent scuffing up the walls).