Like all scoring plays, Nield’s touchdown was reviewed by the CFL Command Centre in Toronto to determine whether the correct call was made on the field. That review lasted an unusually long time before the major was confirmed. The replay official is only able to overturn a call if it is “clear and obvious” that an error has taken place.
Bold above is mine. I didn't know that the burden of proof is so high, but that makes the video review overturn similar to other sports, like baseball and basketball. However, in this case, the video review is always done on a scoring play, which makes one question why the automatic review (that's probably more likely to get it right - multiple angles, not in real time) should be biased by an inferior on-the-field call. Idk what I'd prefer, just thinking about it though...