I own a Tactacam, and I think it's a cool camera to film with. But it does have one MAJOR issue. I installed my Tactacam with scope attachment on my precision 308 Win rifle. I installed it to record my training sessions at Rifles Only when I went last. The big problem I saw right off was a parallax issue when installing the scope extension to record through the scope. I was using a reticle for hold overs and I could not hit anything from about 300 to 600 yards. I took off the scope attachment, and I was able to make my hits just fine. The scope attachment moves the eye relief much further back and causes some issue with the parallax and seeing the target. I'm sure it will work ok for regular hunting scopes and hunting situations where the distance is much closer. But the precision with the scope attachment on had some issues. Otherwise, a very cool unit.
I noticed this too, there was a slight adjustment I did to get them to where I had my parallax was where it should be and the crosshairs were clear and video recording was clear. First few videos I had was blurry, but once I figured it out I didn't have an issue.
I have only used it on my crossbow scope and my burris eliminator III and was able to correct it on both.. but not sure of other models.