These are the real facts on DVT:
A DVT is simply a clot in the venous circulation of the lower limb which MAY give rise to its most fatal complication that of a pulmonary embolism where by the clot blocks off the blood supply to the lungs giving rise to breathlessness...etc. But one must remeber that 65% of all DVTs never end up like this they are simply taken care by the body and never advance to the above stage. The risk groups for DVT:
Post operative patients
Old age
Obesity
The pill
Immobility-chronic
Personally I dont believe you all should get worried by it. The most simplest way to avoid DVT on a long haul flight is to take regular walks if possible or elevate and depress the ankle joint so that you are working the calf muscles....do this often as it aids stagnent bllod flow from the lower limb which may clot, back to the heart. I hope this is of use to you all.