Jun is about to send you a file using ChatSend http://bit.ly/ShowMeFiles?3708000<— This message is appearing in the write box of the chat window as soon as you're about to send/reply a chat message after installing ChatSend. It’s somewhat annoying since before you could type a word in a newly opened chat window, the message will first appear. Nevertheless, this app is cool and best alternative to email when sending a file.
When you click the link above, you shall be brought to the download link (1st image) and the instruction on downloading (2nd image) where it is explained that sharing is done by P2P. After sharing the file (3rd image), you shall be prompted to enter a password to protect the file or leave it blank (4th image).
The receiver shall see a new open tab where an instruction to receive the file can be read. After receiving the file, another instruction is to save the file to your computer.
On the 1st image, you can see the file is already saved to a folder. Meanwhile, just like the rest of Facebook external apps, a post about ChatSend shall be posted on your profile/timeline.