You can give an unmodified copy to Netflix, under the CC BY license. That is the end of the issue, from your perspective, as long as you also follow Netflix rules. Since I have no idea how you would upload content to Netflix, I don't know of any TOS regarding doing this, but I feel confident that there is one. Presumably, in uploading a film, you have to assert certain things and promise to do certain things: you would have to assert that you have the right to upload (or some similar thing), you would have to grant them a license to further distribute, and you probably have to indemnify them against your errors and misdeeds, if they get sued because of what you uploaded.
If, for example, Netflix distributes the movie with some DRM restrictions inserted, that is not allowed by CC-BY, and they should not have done that. They could get sued: then because of that indemnification clause, you may be on the hook. It would all come back to the conditions under which you were allowed to upload the file. If they require you to execute a particular license allowing them to use the file (where the license is more restrictive than CC-BY), you can't do that so don't do that. You may not sublicense the work (always read the actual license).
DRM is a technological measure. If Netflix sets it up so that there are no actual restrictions, then that's okay.
