I had the same problem and it was fixed by doing what the guide that was linked says to do. Open with... navigate to your tb folder and open it with tb.exe. should solve it

Yeah, most people with this problem select the common TB icon usually on their desktop.
You have to browse through your toribash directory and find the actual TB engine/client named "tb" (My Computer<Local Disk<Games<Toribash<tb).

Once you select it, you may want to click on "always use this program to open this type of file", so that you can view replays without the hassle.