I was investigating a bit more.
Rather then in calculating HardDisk Capacities which define G = 1000^3
MediaBay defines G=1024^3
So for example 03 alto sax fill 02: the shown size is 690.88 KB in MediaBay.
690.88 KB = 690.88 * 1024 B = (ca.) 707462
707462 / 1024 = 690,880859375… rounded to 2 decimal digits => 690.88
Of course, there could be a rounding error. So at the end I found out that if I set the MediaBay to this:
Size > equals 707458
The 03 alto sax fill 02 file has been found.
Of course, if you are going to search by using >= or <=, you don’t have to set it so precisely.