When sending an email the largest size of any file or collection of files is 20MB. A 720p HD video recording from your iPhone 4 for 55 seconds probably hits about 20MB (or just under). There isn't a way to increase the email sizing limit, however there are other alternatives such as Microsoft SkyDrive (Free), DropBox (free) and Google Drive (free) which will let you upload and share your files (like you would with email, only slightly different).
If you have a Hotmail/MSN account, you already have SkyDrive and it's easy to setup and use. Just visit: https://skydrive.live.com and sign in using your Hotmail/MSN account.
If you have Gmail (or blogger, or other Google service including YouTube) you can enable and start using Google Drive easily also, just visit: https://drive.google.com/start
If have neither a Google or Microsoft acount, and have no interest in creating an account with either of them, try DropBox. Found here: https://www.dropbox.com