Any% MS is a category in Any% because there are multiple, there is Any% Classic, and Any% NMS (No Mission Skip) Here i will try to tell you about all the categories
Any% MS (Mission Skip) you can use the mission skip feature of the game, any endings can be choosen, can use taxies (but the fastest is to kill Trevor so the A ending)
Any% NMS (No Mission Skip) You can't use the mission skip (but the fastest is the B to kill michael) feature of the game, can use taxies, any endings can be choosen Any% Classic You can't use the mission skip feature of the game, can't use taxies and must choose the C ending of the game
100%-MS need 100% completion of the game, can use taxies and can use the mission skip feature, any endings can be choosen
100%-NMS can use taxies, can't use the mission skip feature of the game, need 100% completion of the game, any endings can bee choosen
100%-Classic can't use taxies, can't use the mission skip feature, need 100% completion of the game, and C ending must be choosen
All Missions Need to complete all Strangers and Freaks, and the story
Segments are just different part of the game. Hope this Helps
Maybe to the category extension.... but i don't think it would really fit there too
Get a second monitor. Thats the only other solution, sadly