It's very common to get crazy high results with Firefox.It's a known issue, been like that for months.
hmmmm it may be chrome.I did the above test in FF which gave me correct speeds. Ive just tried it in chrome and got 472.35 Mbps. Doesn't chrome use some propitiatory flash rather than Adobe.
Just gave speedof.me a go and download wise it wasn't bad, 40.8mbps but apparently my upload speed is 147.64mbps, which seems a little high for my 55/10 FTTC connection.
smf22@lampu:~$ speedtest --list | headRetrieving speedtest.net configuration... 3829) CloudConnX (Eastbourne, Great Britain) [25.26 km] 7028) Proxar IT Consulting (Sevenoaks, Great Britain) [35.16 km] 1675) Custodian DataCentre (Maidstone, Great Britain) [45.27 km] 4740) VooServers Ltd (Maidstone, Great Britain) [45.27 km] 9110) International School of London (Woking, Great Britain) [60.29 km] 226) Structured Communications (London, Great Britain) [62.86 km] 2789) Vodafone UK (London, Great Britain) [62.86 km] 6115) Cybersmart Pty Ltd (London, Great Britain) [62.86 km]11123) Spitfire Network Services (London, United Kingdom) [62.86 km][snip]smf22@lampu:~$ speedtestRetrieving speedtest.net configuration...Testing from BT (5.X.Y.Z)...Retrieving speedtest.net server list...Selecting best server based on ping...Hosted by Custodian DataCentre (Maidstone) [45.27 km]: 14.363 msTesting download speed................................................................................Download: 54.45 Mbit/sTesting upload speed................................................................................................Upload: 14.07 Mbit/s