It seems many previous moderators of this game had different methods of timing than the moderator before him. We would like to change that by defining hard start/end frames for the runs.

The end frame has already been defined: upon loss of control at the end of the run. Therefore, as the rules state, I highly recommend you do something like lie down or point your gun up to make loss of control clear -- otherwise we'll be forced to use a later frame when loss of control is more obvious, which will hurt your time (this is sort of dependent on the category as well). Many runs on the board end time when the final hit is dealt to the final boss. These runs will be re-timed.

The beginning frame is a little tricky. We've decided to use the frame your character's feet touch the ground after exiting the bus. Ideally we would've liked to continue with SDA timing but (1) it's a little less well-defined than when your character's feet touch the ground, and (2) so many runs on the boards already use the "feet touch the ground" start-point we figured it would be a pain to re-time all of them.

I hope all of these new changes will be welcomed. We'll re-time the runs on the board which don't meet this criteria.

I was thinking about the start timing and landing on feet is flawed because Browny can use his 2nd jump before touching the ground causing a delayed start. 

A consistent start time method would be the first frame of the vehicle's window being broken, you are still able to fire your gun (aka gaining some control) before landing on the ground.

When I end my runs, I always walk to the point the game forces my character to stop.

I like that idea Greenalink. Since the car is not a flickering object (like your character at the beginning) it won't be so difficult to frame-count runs recorded at 30fps (which sometimes appear invisible when recorded at 30fps).

I'll see what nickbgohard has to say.

No further changes to the rules as listed above. If you choose to hover jump with Browny before hitting the ground the first frame of the boost will be the start.  No old runs will be re-timed unless it prevents a new submission from reaching a higher position.