Send lets you upload and encrypt large files (up to 1GB) online. It's generate a auto expire in 24hr download link of you file. Also you sat a password and select how many time its download. I test it and it's work fine upload speed was good. Shearing a encrypted link is more safer then send file by google drive or drop box. When you use Send, Mozilla receives an encrypted copy of the file you upload, and basic information about the file, such as filename, file hash and file size. Mozilla does not have the ability to access the content of your encrypted file, and only keeps it for the time or number of downloads indicated.
Try somthinge diffrent to learn new things