>>/160070/
"C:\Windows\System32\drivers\etc\hosts"を見てみましたが中身は空（コメントアウトがあるのみ）でした

> # Copyright (c) 1993-2009 Microsoft Corp.
> #
> # This is a sample HOSTS file used by Microsoft TCP/IP for Windows.
> #
> # This file contains the mappings of IP addresses to host names. Each
> # entry should be kept on an individual line. The IP address should
> # be placed in the first column followed by the corresponding host name.
> # The IP address and the host name should be separated by at least one
> # space.
> #
> # Additionally, comments (such as these) may be inserted on individual
> # lines or following the machine name denoted by a '#' symbol.
> #
> # For example:
> #
> #      102.54.94.97     rhino.acme.com          # source server
> #       38.25.63.10     x.acme.com              # x client host
> 
> # localhost name resolution is handled within DNS itself.
> #	127.0.0.1       localhost
> #	::1             localhost

プロキシ設定は「設定を自動的に検出する」がオン、「セットアップスクリプト」がオンでhttp://127.0.0.1:8080/proxy.pacになっているので合ってますよね。
「設定を自動的に検出する」は要らないのかな？
そもそもプロキシをオフにしてもnicoad.nicovideo.jpにアクセス出来ない。