I think this one is a must watch.
Potrblog has very carefully tried to validate their findings by checking the reliability of their measurements and subtracting background levels from their detections.
They used two geiger counters, checked for reliability (i.e., consistency) of measurements.
They used a sample collected on April 14, which measured 49X background radiation.
They put the radioactive sample material in their lab (a lead cave in a lead-lined box) with a geiger counter. This is the experimental condition.
They put another geiger counter in the same lead-lined box, but in a separate lead-lined cave. This is their control condition.
(Regarding time in cave: I cannot see the chart but the X axis has more than 8000 minutes)
They graphed the data from the time spent in cave for the control and experimental geiger counter conditions.
They subtracted the background measurements detected on the control geiger counter from the measurements of the radioactive rain sample (experimental condition).
The experimental condition (precipitation sample) data were significantly higher than the zero line after subtracting background data measured in the control condition.
Their detections of longer half-life fallout match Cesium-134 and Bismuth 212, but they cannot guarantee the validity of these identifications.
[Note: they also detected high levels of radon daughters. Potrblog thinks that radon daughters are being steamed out of ground in Fukushima (which has high concentrations of radon in ground water naturally) when nuclear criticalities occur at the plant.
I very much appreciate Potrblog's efforts to make their methods transparent for critical discussion and debate.