Generic AVerMedia TV Tuner drivers for Windows 7 (64-bit) are available on Lenovo Support .
For legacy hardware (2010 and earlier), the only safe source is the original manufacturer’s archive or a community repository with checksums. Driver Avermedia A857 Windows 7 64 Bits LINK
Before installing the software, verify that your hardware matches the specifications of this specific TV tuner model: USB 2.0 Generic AVerMedia TV Tuner drivers for Windows 7
The safest starting point is the AVerMedia Download Center . While legacy models are occasionally archived, entering "A857" or using their AVerMedia Assist Central Driver Avermedia A857 Windows 7 64 Bits LINK