That red part in the middle, or the thin line? Now figure in the fact that it moves, and waves, thats a flag thing. Oh wait, someone came to their senses, oh my, what next???
http://www.mxsportsproracing.com/articles/1290_race-report-1---procedural-improvements , "Safety Flag:
Based on input from various sources, we are going to change the color of the "wheels on the ground flag" from yellow with red to white with red. Most riders agreed that this would enhance visibility. In addition, the white and red color scheme is consistent with the Red Cross flag used in Supercross which virtually means the same thing (no jumping or passing). We firmly believe in the purpose of the flag, and welcome any suggestion to improve visibility. AMA Pro Racing will be issuing a Technical Bulletin announcing the new flag color scheme forthwith.
In addition, during the first lap of free practice, as well as the sighting laps before each moto, we will display this flag at all locations so that riders will know where the flags will be. You still must roll this section even during the free practice and sight laps. We will also have track maps available at the MX Sports semi showing where the flags will be located on the track."