Even though this is not part of the question I'd like to point out that "Sportfilm" is a noun and therefore has to be written in uppercase.
Now regarding your claim:
If you refer to the movie itself it should be "Er" and "Der" as Martin Peters wrote. But referring to the movie using "der" is kind of clumsy.
If you instead vaguely refer to the action of purchasing the movie "Es" and "Das" would be ok.
A middle ground would be "Der Sportfilm! Er kostet 4€. Das ist billig." Like this you would directly refer to the movie as an entity in the second sentence while referring to the fact that its cheap in the third.
Let me give you another example.
"The woman. She is beautiful. She is nice." would translate to "Die Frau. Sie ist schön. Sie ist nett."
Instead "The woman. She is beautiful. That is nice." would translate to "Die Frau. Sie ist schön. Das ist nett."
I hope this helps clarifying the difference.