using different video definitions

I have given an in depth segment on my blog as to what different definitions are however, I am going to comment on the reasons why I exported my music video at the resolution I did.
So I exported at a resolution of HD ready 720p, even though I filmed in 1080p. The reason for this is that I want everyone to be able to view my product and this cant happen if it is in the highest resolution HD,  because not everyone has the viewing platform to be able to watch such high quality items. So not everyone wold be able to watch my video and so this is why I exported in this resolution.