Synthesia plays well midi file without any note off event?

Question

I have a .mid file - this one specifically. Appart from the header chunk here is the relevant part of the midi. The first track chunk contains only meta events and

Answer 1

96 40
      90 4B 50 // Midi "Note on" event
81 63
         4B 00 // Midi "Note on" event because of running status
            ^^

The MIDI specification says:

MIDI provides two roughly equivalent means of turning off a note (voice). A note may be turned off either by sending a Note-Off message for the same note number and channel, or by sending a Note-On message for that note and channel with a velocity value of zero. The advantage to using "Note-On at zero velocity" is that it can avoid sending additional status bytes when Running Status is employed.

Due to this efficiency, sending Note-On messages with velocity values of zero is the most commonly used method.