The first 2 parameters of WinMain are HINSTANCEs, not HANDLEs.

programs/avitools/aviinfo.c

@@ -7,7 +7,7 @@
 #include "vfw.h"
 
 
-int PASCAL WinMain (HANDLE hInstance, HANDLE prev, LPSTR cmdline, int show)
+int PASCAL WinMain(HINSTANCE hInstance, HINSTANCE prev, LPSTR cmdline, int show)
 {
     int			n;
     HRESULT		hres;

programs/avitools/aviplay.c

@@ -28,7 +28,7 @@
 #include "vfw.h"
 
 
-int PASCAL WinMain (HANDLE hInstance, HANDLE prev, LPSTR cmdline, int show)
+int PASCAL WinMain(HINSTANCE hInstance, HINSTANCE prev, LPSTR cmdline, int show)
 {
     int			bytesline,i,n,pos;
     time_t		tstart,tend;

programs/avitools/icinfo.c

@@ -5,7 +5,7 @@
 #include "vfw.h"
 
 
-int PASCAL WinMain (HANDLE hInstance, HANDLE prev, LPSTR cmdline, int show)
+int PASCAL WinMain(HINSTANCE hInstance, HINSTANCE prev, LPSTR cmdline, int show)
 {
     int n=0,doabout=0,doconfigure=0;
     char	buf[128],type[5],handler[5];