Is forcing users to signup after clicking a play button a dark pattern?

Im in a tricky situation.

We are creating a page with a live video stream that in order for the user to view it they need to sign up for an account. I created a page where there is a clear action to sign up, using a button with an overlay. I can't share with you the actual designs but here is an abstracted version of it:

First step: The user is prompted to sign up or log in, the thumbnail of the video has an overlay

Second step: The user having either registered or signed in can now play the video:

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However the stakeholders for this project wants the process to start with a play button, like this:

First Step: The user clicks the play button in order to view the video

Second Step: The user then needs to complete a login or registration process in order to view the video

One of the main arguments for this is that the button is smaller and less obstructive to the thumbnail beneath it, which makes for a more visually engaging page. And i get that.

However, it strikes me that this might be a dark pattern, clicking a play button should just start the video, not prompt a registration process. However i have noticed other very established sites use this pattern. Here is an example from the BBC iPlayer:

This BBC example is being used to push through this change but i feel that this might be a dark pattern.

So should I speak up? is this a dark pattern? If so how serious is it?