What he says is partially true. A large number of locals often bring up the 3:1 exchange rate and use this to show whose e-peen is larger.
What I disagree with foremost, is that the video is saying Singaporeans think Malaysia is weaker. This is entirely different from thinking that Malaysia is weaker economically.
Saying that I think John is weak in Maths, is different from saying that I think John is weak.
I would go so far as to call out the message as akin to putting words into my mouth and mislead people by saying that
"Orphan thinks John is weak. My proof is that he thinks John is weak in maths."
I do however, acknowledge that the large number of people using 3:1 comparison can mislead less discerning folks into the impression that these Singaporeans consider Malaysia a weaker country simply because of the 3:1 currency rate. Again, it tends to affect easily infuenced folks, which sadly includes the video creator.
In truth, what needs to be considered, is that Singaporeans do not use currency strength to compare with our other ASEAN neighbors with a robust economy like Indonesia, Thailand, Vietnam etc.
Why only Malaysia?
One reason of coz, is because they are our nearest neighbor. We know more about them and are more closely knit with them than other neighbors.
Secondly, there is definitely also the concern regarding the ease of how a large number of people from our nearest neighbor is taking local jobs. In other words, whether we admit/realize it, we feel threatened in certain aspects.
In my opinion, a more probable cause is due to 2 things:
The lesser reason is there was a time where Singapore, Malaysia (and Brunei) currencies were worth the same and can be used interchangebly. Malaysia pulled out of this agreement later one, and the from 1:1, it became 1:2, and then 1:3.
The impression is like seeing someone who was our equal, becoming weaker.
If there never was such a time when our currencies were once equal, I doubt this 3:1 exchange rate will be brought up just like we do not bring up comparisions between Indonesia Rupee and Sing dollar.
The other important reason why Singaporeans feel that Malaysia has a weaker economy is due to salary differences in similar jobs even after factoring in currency differences. A position here that pays 3k SGD, may only pay 6k ringgit in Malaysia. Converting to SGD at 3:1, it means Malaysians are being paid 2k SGD for the same job.
Yes, there are more factors, like the video correctly mentioned, there are differences in economies revolving around Manufacturing (or Produce) vs economies centered on being a trade hub.
There's also something called the resource curse which often plagues production economies.
Overall, there are many more factors that cannot fit into a forum post or a short video to explain the how strengths of different enconomies are determined/viewed/achieved and the absolute neccessity of economies centered around both trading and agriculture/ production/manufacturing.