I just solved the problem myself. After switching smbios product definition (using Multibeast) from iMac14.2 to MacPro6.1, I don't see crashes any more.
So, if you ever run into problem like this, especially see the following in crash report, try to play with system definition.
Crashed Thread: 7 Dispatch queue: com.apple.flexo.playertokq.sched
Exception Type: EXC_BAD_INSTRUCTION (SIGILL)
Thread 7 Crashed:: Dispatch queue: com.apple.flexo.playertokq.sched
0 libsystem_platform.dylib 0x00007fff98559caf _os_lock_corruption_abort + 0
1 libsystem_platform.dylib 0x00007fff9855886b _OSSpinLockLockSlow + 125
2 libsystem_pthread.dylib 0x00007fff9999f77d pthread_mutex_destroy + 25
3 com.apple.AppleGVAFramework 0x0000000147372805 0x147324000 + 321541
4 com.apple.AppleGVAFramework 0x000000014737cf4c 0x147324000 + 364364
5 com.apple.VideoToolbox.ProAppsSupport 0x00000001112a7c9d 0x11122d000 + 502941
6 com.apple.VideoToolbox.ProAppsSupport 0x0000000111234e8d VTDecompressionSessionCreateWithOptions + 1606
7 com.apple.VideoToolbox.ProAppsSupport 0x0000000111234f2f VTDecompressionSessionCreate + 20
8 com.apple.Flexo 0x000000010fad777f CoreMediaMovieReader::createDecompressionSession(__CFString const*, bool) const + 255
9 com.apple.Flexo 0x000000010fad737f CoreMediaMovieReader::CoreMediaMovieReader(opaqueCMFormatDescription const*, __CFDictionary const*, bool, bool) + 719
10 com.apple.Flexo 0x000000010fade527 FFVideoDecoder::createCoreMediaMovieReader(bool, bool) + 71
11 com.apple.Flexo 0x000000010faddff9 FFVideoDecoder::FFVideoDecoder(opaqueCMFormatDescription const*, unsigned int, FFSVQualityEnum) + 633