Video upload limit

I am creating a webpage through WordPress with an EasyTech theme. I am trying to load videos on my webpage but I am having a really hard time because it only allows me a video of 45mb or less. The videos I created are from 160mb to 300mb. I compressed the videos down with a free website, Freeconvert.com but when I tried uploading the video to my site, they appeared black and didn’t play. My videos are .mp4 but I know that I can also convert them to .mkv. Any suggestions on either increasing the 45 mb upload limit or reducing the file size and uploading the videos? Thank you very much.