There is no option to mark your videos as mildly sexual so they don't get taken down.

 

If a user flags your video, staff reviews it and decides what, if any action to take.

 

If you believe staff may age-restrict your video and you do not wish that to happen, then edit out the parts that might result in an age restriction.

 

And, obviously, if you believe staff will disable the video for violating the Term of Service, don't upload it at all.