How would you go about finding out when a digital video was made? How can you determin when a digital video was made? I know one possibility would be just looking at the meta data but sometimes they are faked or missing. I need some more ideas since I have to write 10 pages about it...

Is there any trick like figuring out what codec was used recording the video, and that this codec is only used by this type of phone, that is only available since then and so the video can not be older than...

I need some ideas in this direction but I am stumped. One idea I have is to analyze the picture quality of multiple copies of the video found online and since every recoding results in loss of quality, you could try to determin which one might be the first since it has the best quality.

But this would only be one method. Any help would be brilliant! I don't expect ready to use answers but suggestions would be wonderful! I am hoping to find something in the line of the Kodak Edge Codes but for digital videos.
When data is in digital format they can be manipulated in any way you want, so the initial data would not be certain in any way.

Videos on mobile phones is a fairly recent thing, however video over phone is nothing new and the first video capable phones are based on codecs back from the 80's. Only the later years you will see phones with more modern video formats due to the increased processing power of the phone.

Meta data and it's possible date data can be wrong. See if you can get the phone's brand and model from the meta data - then you can establish a more accurate period as phones come and go at a rather fast pace.

Then you can combine these data (codec used) to see if you have some overlap time-wise.