STEP 1/6
not from the personal channel but from "home video" page and select the "Save Change"
STEP 2/6
select "3D Video" tab
STEP 3/6
select your 2D video
STEP 4/6
flag the "Enable 3D conversion for this video" and Save the change
STEP 5/6
STEP 6/6
now is enable the 3D icon below the video
