Why it's 2/3,not 1/3?

"Since the second train (purple) in the picture covers the distance from one dotted line to another, you will only cross ⅓ of this distance in the same time, so you will be ⅔ of the way past your original position at where train 1 passed you."
I don't understand this sentence from above from the You Turn Explanation. 
Can you give me which explanation video (out of 3) and video time at that statement

@studiouszebra it is the Your Turn Explanation 2 of 3.

@energizeddog Because Green train(Your Train) already made 20 miles when Green train met Purple train so it already covered 1/3 distance in 1 hour compared to Purple train can cover in 1 hour then 1/3 more in another 60 mins. So therefore green train traveled 1/3 + 1/3 = 2/3 distance compared to purple train can cover in 1 hour from when Green Train started.

@studiouszebra Do you think this is the explanation sir ? If I missed a point please let me know.

@studiouszebra thanks for your explaining. Now I can understand why it's 2/3.

@energizeddog Welcome Sir.