As I understand it a link to the file appears in-game at the end of a round if the feature is turned on, so the files will either be available to both teams or neither team.
If reports are accurate the file will allow you to replay the game and watch it from any angle you like, allowing you to cheack out the opposing team's tactics. This goes both ways though, and I think the advantages of being able to go over your own team's performance and being able to make the files available to members of the clan who didn't play in that match will outweigh the disadvantage of giving away tactics. It just means clans won't be able to play a map the same way every time. This isn't far off how things currently work anyway; when you use a plan and it works well the opposing clan will usually pick up on what you did.