It is absolutely nothing to worry about, just a warning to you that the this site does not operate as securely as possible.

It is FT, not your bank... so not the same level of security needed. It is not a site through a HTTPS link which would be more secure and have the little green lock symbol.

It just indicates to you that it could be intercepted by a malicious third party as the details it passes from end to end are not encrypted in transit.

I am keeping this explanation as low level tech as I can, as I think that is as much as needs to be said about it! Just before a fully unintelligible hi-tech explanation is offered