需要修改web.config配置文件:

<?xml version="1.0" encoding="UTF-8"?>
<configuration>
	<system.webServer>
		<directoryBrowse enabled="true" />
		<security>
			<requestFiltering allowHighBitCharacters="true" allowDoubleEscaping="true" />
		</security>
        <staticContent>
            <mimeMap fileExtension=".mkv" mimeType="video/x-matroska" />
        </staticContent>
	</system.webServer>
</configuration>

设置allowHighBitCharacters 后 即可正常访问,设置.mkv格式mine后,才能正常下载