Quite often it’s not Blink hardware, nor their servers that are the problem. Gotta remember there are hundreds of thousands maybe even millions of Blink cameras sold over the years that are working with the mobile app just fine.
What has been reported over and over in this community forum is…issues/conflicts with the customer’s home network. Another problem is customer’s mobile device they are using doesn’t work well with the Blink mobile app. Blink does not guarantee performance and suitability for every combination of home network and mobile devices that are out there all over the world.
Try a different mobile device on a temp basis to do more testing. Shut off other devices on your home network to isolate just Blink running. If non of that fixes your Blink clip playback problems, it’s time to get your 30 day refund kicked in aka get your money back.