If i converted 1080 to 720?

Would it look better. I'm doing videos with a nikon d3100 and they mostly go on youtube so if i were to film in 1080 and convert to 720 during editing would it look better or would that cause problems

Rather leave the videos in 1080p. Higher resolution is better anyway.

Why convert to 720p? 1080p provides the better quaity than 720p, of course, the 720p still be good for youtube. I have nikon d3100 too, if you want to make and upload good youtube videos from the nikon d3100 recorded videos, you can simply follow me to use Youtube Movie Maker, it can be used to make/edit and upload videos for youtube from various videos, pictures, audios, musics, words, lyrics, subtitles, etc. And it provides many video/audio editing features, such as cut, crop, trim, split, rotate, join, merge, add musics, mix musics, put multiple videos together, mix multiple videos on same screen, speed up/down, add cool font texts/lyrics, add special effects, add transition effects, add motion/action, add video shapes, etc. You can download this software from makeyoutubevideo.com, and view below channel for some online guides, youtube.com/easymakevideo, if my answer helps you, please give me Best Answer, thanks.

It would look better in 1080, however 720 will upload and stream much more efficantly. The major problem with most YouTube videos is that the file is compressed incorrectly or a bad CODEC choice. I would say pick either resolution and compress it to an H.264 file. It allows for good video and audio without being a larger file like say an. MOV. Also YouTube viewers don't always have the capability of viewing high res videos (Internet speed, moniter, graphics, ect) do a test video and see how well it plays on different computers and different ip address'. Hope I could help.

Sorry, but the conversion process only makes your video quality worse regardless of the video size.