I know it's got to deal with movement. However, there's a lot of talk of people abusing this by moving side to side in corners. What if running forwards or walking forward was considered "actively moving" with a one second grace period toward walking or running (for reloading, etc.)
That way if anyone wanted to stay in a corner the majority of the match they'd have to continuously walk forward, turn around, and walk towards it again. Thus, you have an almost complete elimination of people staying in one spot on the map, undetected.