No Windows, esta é a pasta de cache do Google Chrome:
C:\Users\<user-name>\AppData\Local\Google\Chrome\User Data\Default\Cache
No entanto:
A técnica de cache do Google Chrome é defensiva!
Although you could use YouTube downloader program or manually retrieve the YouTube video direct download link to keep a copy of the video for your mom who only like to watch them on the classic TV + player set, you might need to use non-Google Chrome web browsers to retrieve the FLV files on some less popular video hosting sites, via the web browser cache folder technique.
Leia este excelente post para mais algumas informações (embora possa estar desatualizado)