download and install jre 

https://www.java.com/en/download/manual.jsp

https://www.java.com/en/download/

download microemulator

https://sourceforge.net/projects/microemulator/files/microemulator/2.0.4/

https://sourceforge.net/projects/microemulator/files/latest/download

download opera mini jar

https://www.opera.com/download/mobile-versions

http://mini.opera.com/download-7/opera-mini-latest-advanced-en.jar

http://mini.opera.com/download-4/opera-mini-latest-advanced-en.jar

jad = Java Application Descriptor, just metadata 

jar = Java Archive

run

extract microemulator zip file 

cd C:\Users\acer\Downloads\Compressed\microemulator-2.0.4

or 

cd %USERPROFILE%\Downloads\Compressed\microemulator-2.0.4

java -jar microemulator.jar

file > open midlet file > select opera mini jar file downloaded 

for resizeable device options > select device > resizeable device and set it default 

https://help.opera.com/en/opera-mini-and-javascript/

java.exe -cp microemulator.jar;lib/microemu-jsr-75.jar org.microemu.app.Main –impl org.microemu.cldc.file.FileSystem org.microemu.examples.fcview.FCViewMIDlet opera-mini-latest-advanced-en.jar

notepad C:\Users\acer\.microemulator\config2.xml

notepad %USERPROFILE%\.microemulator\config2.xml

add this before </ config> and save

<extensions>
    <extension>
        <className>org.microemu.cldc.file.FileSystem</className>
        <properties>
            <property value="C:\" name="fsRoot"/>
        </properties>
    </extension>
</extensions>

 bestvideo+bestaudio/best

4320p (8K) : 7680 × 4320 pixels

2160p (4K): 3840 × 2160 pixels

1080p (Full HD): 1920 × 1080 pixels

720p (HD): 1280 × 720 pixels

480p (Standard Definition): 854 × 480 pixels

360p : 640 × 360 pixels

240p : 426 × 240 pixels

144p: 256 × 144 pixels

 YouTube videos generally use a 16:9 aspect ratio (widescreen)