In the first version of the Test Data Collector I've used .NET binary serialization. This has turned out to be too inflexible.
v2 of the TestDataCollector saves the data as XML. The depth frame is encoded as base 64 byte array inside the XML. This results in a larger file size, but the hand data is human readable and no type information is saved within the file.
v2 can still open the old files. They can then be saved in the new format.
I've updated the download on CodePlex.
Warning: v3 will not be able to read the old binary tfrm files anymore, you have to use v2 to convert them!